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Takashi Tokumasu

Section

Institute of Fluid Science

Job title

Professor

Degree

博士（工学）（東京大学）
修士（工学）（東京大学）

researchmap

https://researchmap.jp/read0191511

J-GLOBAL ID

200901088830246820

Research History 5

2017/04 - Present

Tohoku University　Institute of Fluid Science　Professor
2007/04 - 2017/03

Tohoku University　Institute of Fluid Science　Associate Professor
2005/12 - 2007/03

Institute of Fluid Science, Tohoku University　Associate Professor
2003/04 - 2005/11

Institute of Fluid Science, Tohoku University　Lecturer
1999/04 - 2003/03

Institute of Fluid Science, Tohoku University　Research Associate

Education 2

The University of Tokyo　Graduate School, Division of Engineering　Mechanical Engineering

- 1998/03
The University of Tokyo　Faculty of Engineering　Machenical Engineering

- 1992/03

Committee Memberships 14

日本機械学会流体工学部門　広報委員

2011/04 - Present
日本機械学会マイクロ・ナノ工学部門　表彰委員

2012/04 - 2015/03
日本機械学会　流体工学部門表彰委員会幹事

2010/04 - 2011/03
日本機械学会　流体工学部門表彰委員会幹事

2010/04 - 2011/03
日本機械学会　流体工学部門表彰委員会

2009/04 - 2010/03
日本機械学会　流体工学部門表彰委員会

2009/04 - 2010/03
日本航空宇宙学会　北部支部幹事

2002/04 - 2010/03
日本航空宇宙学会　北部支部幹事

2002/04 - 2010/03
日本機械学会熱工学部門学会賞委員会　幹事

2008/04 - 2009/03
日本機械学会熱工学部門学会賞委員会　幹事

2008/04 - 2009/03
日本機械学会　校閲委員

2007/04 - 2008/03
日本機械学会　校閲委員

2007/04 - 2008/03
日本機械学会　校閲委員

2006/04 - 2007/03
日本機械学会　校閲委員

2006/04 - 2007/03

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Professional Memberships 4

the electrochemical society of Japan
日本混相流学会
Aeronautical and Space Science Japan
日本機械学会

Research Interests 4

All solid state Li ion battery
Nacoscale Flow Dynamics
Fuel Cell
Molecular Dynamics

Research Areas 1

Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Fluid engineering / Rarefied Gas

Awards 5

Frontier Award

2020/11　Flow Engineering Division, Japan Society of Mechanical Engineering
Contribution Award

2019/11　Micro-Nano Science and Technology, Japan Society of Mechanical Engineering
Presentation Award

2016/10　Thermal Engineering Division, Japan Society of Mechanical Engineering　分子動力学法を用いた高分子電解質膜内におけるプロトン輸送現象の解析
Certificate of Merit of Contribution

2013/11　Fluid Engineering Division, Japan Society of Mechanical Engineering
日本機械学会奨励賞(研究)

2000/05　日本機械学会

Papers 307

Crystal orientation of epitaxial film deposited on silicon surface

Satoru Kaneko, Takashi Tokumasu, Manabu Yasui, Masahito Kurouchi, Daishi Shiojiri, Shigeo Yasuhara, Sumanta Kumar Sahoo, Musa Mutlu Can, Ruei Sung Yu, Kripasindhu Sardar, Masahiro Yoshimura, Masaki Azuma, Akifumi Matsuda, Mamoru Yoshimoto

Scientific Reports　14　(1)　2024/05/13
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41598-024-61564-8 　

eISSN： 2045-2322

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Abstract Direct growth of oxide film on silicon is usually prevented by extensive diffusion or chemical reaction between silicon (Si) and oxide materials. Thermodynamic stability of binary oxides is comprehensively investigated on Si substrates and shows possibility of chemical reaction of oxide materials on Si surface. However, the thermodynamic stability does not include any crystallographic factors, which is required for epitaxial growth. Adsorption energy evaluated by total energy estimated with the density functional theory predicted the orientation of epitaxial film growth on Si surface. For lower computing cost, the adsorption energy was estimated without any structural optimization (simple total of energy method). Although the adsorption energies were different on simple ToE method, the crystal orientation of epitaxial growth showed the same direction with/without the structural optimization. The results were agreed with previous simulations including structural optimization. Magnesium oxide (MgO), as example of epitaxial film, was experimentally deposited on Si substrates and compared with the results from the adsorption evaluation. X-ray diffraction showed cubic on cubic growth [MgO(100)//Si(100) and MgO(001)//Si(001)] which agreed with the results of the adsorption energy.
Molecular Dynamics Study of the Microscopic Mechanical Balance at the Three-Phase Contact Line of Interfacial Nanobubble

Yusuke Jonosono, Shin-ichi Tsuda, Takashi Tokumasu, Hiroki Nagashima

Langmuir　40　(16)　8440-8449　2024/04/11
Publisher: American Chemical Society (ACS)
DOI： 10.1021/acs.langmuir.3c04027 　

ISSN： 0743-7463

eISSN： 1520-5827
Reactive Force Field Molecular Dynamics Studies of the Initial Growth of Boron Nitride Using BCl<inf>3</inf> and NH<inf>3</inf> by Atomic Layer Deposition

Naoya Uene, Takuya Mabuchi, Masaru Zaitsu, Shigeo Yasuhara, Adri C.T. van Duin, Takashi Tokumasu

Journal of Physical Chemistry C　128　(3)　1075-1086　2024/01/25

DOI： 10.1021/acs.jpcc.3c06704 　

ISSN： 1932-7447

eISSN： 1932-7455
The role of the drying process and the Pt/C structure on the ionomer morphology of the catalyst layer

Yuting Guo, Takuya Mabuchi, Gaoyang Li, Takashi Tokumasu

Surfaces and Interfaces　44　2024/01

DOI： 10.1016/j.surfin.2023.103731 　

ISSN： 2468-0230
A Molecular Dynamic Study on the Prediction of Novel 2D Nanoadditive Performance in Palm Oil Methyl Ester (POME)-Based Lubricant

Rizky Ruliandini, Takuya Mabuchi, William Goncalves, Saidur Rahman, Takashi Tokumasu, Nasruddin Nasruddin

Journal of Bio- and Tribo-Corrosion　9　(4)　2023/12

DOI： 10.1007/s40735-023-00804-2 　

ISSN： 2198-4220

eISSN： 2198-4239
Molecular dynamic study of oxygen ion diffusion and grain boundary in SrSc0.1Co0.9O3-δ perovskite solid oxide membrane

Hiroki Nagashima, Ryan Falkenstein-Smith, Jeongmin Ahn, Takashi Tokumasu

Solid State Ionics　399　116291-116291　2023/10
Publisher: Elsevier BV
DOI： 10.1016/j.ssi.2023.116291 　

ISSN： 0167-2738
Molecular analysis of hydrogen-bond structures in polymer electrolyte membrane in polymer electrolyte fuel cells below freezing temperatures

Hiroki Nishizawa, Takuya Mabuchi, Naoya Uene, Takashi Tokumasu

ECS Transactions　112　(4)　285-290　2023/09/29
Publisher: The Electrochemical Society
DOI： 10.1149/11204.0285ecst 　

ISSN： 1938-5862

eISSN： 1938-6737

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The PEFC has been attracted to achieve carbon neutralization with using of cars and so on. Unclearness of the internal state of the polymer electrolyte membrane (PEM) below freezing temperature is one of the biggest problems toward expansion of operating temperature. Our final objective is to reveal the internal state of PEM and transport mechanism in such environment. We performed the reactive force field molecular dynamics to analyze the internal structure of PEM because under such environment chemical reaction is the key transport mechanisms. A radial distribution function (RDF) was performed to analyze the structure in PEM. Our RDF was in good agreement with other simulation results. We found the increase of water molecules in the overlapped solvation area with the decrease in temperature. The water molecules hardly move in the overlapped area, indicating that proton diffusivity decreases.
Molecular Dynamics Analysis of the Scattering Phenomena of Oxygen Molecules on an Ionomer Surface in Catalyst Layer of Fuel Cell

Keisuke Mizuki, Takuya Mabuchi, Ikuya Kinefuchi, Takashi Tokumasu

ECS Transactions　112　(4)　361-368　2023/09/29
Publisher: The Electrochemical Society
DOI： 10.1149/11204.0361ecst 　

ISSN： 1938-5862

eISSN： 1938-6737

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The purpose of this study is to clarify the effect of surface diffusion, which is the behavior of gas molecules on ionomer thin films, on the transport properties of oxygen in fuel cell catalyst layers. To this end, the direct simulation Monte Carlo (DSMC) and molecular dynamics (MD) methods were used in our simulations. The results of the DSMC method showed that the overall transport is strongly affected by the behavior of surface diffusion. It was found that the diffuse reflection model for surface diffusion used in the DSMC method has room for improvement as the MD results show a different trend that oxygen molecules tend to reflect in the direction of travel.
Analysis of structural and water diffusional properties of ionomer thin film by coarse-grained molecular dynamics simulation Peer-reviewed

Yuting Guo, Sheng-Feng Huang, Takuya Mabuchi, Takashi Tokumasu

Journal of Molecular Liquids　2023/09

DOI： 10.1016/j.molliq.2023.123190 　
Oxygen Ion Conduction Property of Solid Oxide Membrane Based on Multi-scale Analysis

Takumi Ijichi, Hiroki Nagashima, Alexander Hartwell, Jeongmin Ahn, Takashi Tokumasu

ECS Meeting Abstracts　MA2023-01　(54)　247-247　2023/08/28
Publisher: The Electrochemical Society
DOI： 10.1149/ma2023-0154247mtgabs 　

eISSN： 2151-2043

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In recent years, various environmental problems such as rising temperature, droughts, and extreme weather events have become more serious in many parts of the world because of global warming. One of the causes of the global warming is an increase in emissions of greenhouse gases such as CO₂, CH₄, and N₂O, those are emitted during a combustion of fossil fuels such as coal, oil, and natural gas in thermal power generation. As energy consumption accelerates year by year, the depletion of fossil fuels is also becoming an issue. Therefore, hydrogen energy is attracting attention. Hydrogen is known as a clean energy because it reacts with oxygen to produce only water and chemical energy. Fuel cells are attracting attention as a new power generation device that produces electricity from hydrogen energy. Fuel cells generate electricity directly through chemical reactions, resulting in minimal power generation loss from energy conversion. Solid oxide fuel cells (SOFC), in which solid oxide electrolyte membrane (SOEM) is used as the electrolyte membrane, have particularly high-power generation efficiency. On the other hand, the operating temperature of SOFCs is extremely high (over 1000 K), which accelerates degradation of SOEM. Therefore, it is necessary to lower the operating temperature from high to medium (about 700 K) while maintaining high power generation efficiency. To solve this problem, we focus on dual-phasing and nano-structuring of SOEMs. Previous studies of SOEM have shown that dual-phase membranes have better ion transport performance than a single-phase membrane. For example, a dual-phase SOEM is composed of SSC (SrSc_0.1Co_0.9O_3-d) with perovskite structure and SDC (Sm_0.2Ce_0.8O_2-d) with fluorite structure. One the other hand, nano-structuring are nano-thin film and nano-crystalline. Nano-thin film is a method of forming an electrolyte film of several μm by layering nano-films of several nm in size. Nano-crystalline is a method to reduce a crystal size to several tens of nanometers. By these nano structures, the resistance of ion conduction is reduced, and ion conductivity is improved. However, the number of interfaces in dual-phase SOEM and nano structured membrane is expected to increase. Previous studies have reported a decrease in ion conductivity near the interface between different structures of membrane. This decrease in ion conductivity at the interface is caused by an increase in the energy barrier as the conduction path passes through the interface. The correlation between the reduction of ion conductivity and nano structures in membrane has not been clarified clearly. In this study, we analyze the mechanism of oxygen ion conductivity reduction near the interface by numerical simulations. Molecular simulations are performed to build up information by multi-scale analysis. Specifically, density functional theory (DFT), molecular dynamics (MD), and kinetic Monte Carlo (kMC) are performed in a bottom-up manner. First, MD simulations were performed using a potential model constructed from the energy states in the atomic arrangement at the interface obtained by DFT. We analyzed the ion conductivity at the interface and its crystal size dependence. We also create a hopping model of oxygen ions moving from site to site for kMC simulations. Next, kMC simulations are performed to analyze the oxygen ion conductivity in the dual-phase SOEM including interface, on a time and spatial scale similar to that of a real SOEMs. In this presentation, we report on the results of MD simulation. A dual-phase SOEM model consisting of SSC and SDC was used as the simulation model (Fig.1(a)). The diffusion coefficient of oxygen ions was obtained as an indicator of ionic conductivity. Because the ionic conductivity is determined by the balance between the energy barrier of the conduction path and the kinetic energy of the ions involved in ionic conduction. In this study, the activation energy for the diffusion was calculated as the energy barrier. The activation energy was estimated from Arrhenius relation of diffusion coefficient. The number of unit cells in the dual-phase SOEM model was varied to change the crystal size. As a result, both the diffusion coefficient and activation energy increase as the crystal size of SSC increases. On the other hand, as the crystal size of SDC increases, although the diffusion coefficient decreases, the activation energy increases (Fig.1(b)). These results show the dependence of the diffusion coefficient and activation energy on the crystal size in a dual-phase SOEM. Figure 1 <p></p>
Reactive Force Field Molecular Dynamics Study of the Effects of Gaseous Species on the Composition and Crystallinity of Silicon–Germanium Thin Films

Naoya Uene, Takuya Mabuchi, Masaru Zaitsu, Shigeo Yasuhara, Takashi Tokumasu

Crystal Growth & Design　2023/05/26
Publisher: American Chemical Society (ACS)
DOI： 10.1021/acs.cgd.3c00240 　

ISSN： 1528-7483

eISSN： 1528-7505
The evaluation of density and diffusion properties in hydrogen/oxygen mixture modelled by Lennard-Jones fluid

Takumi Ijichi, Shin-ichi Tsuda, Takashi Tokumasu, Hiroki Nagashima

Molecular Physics　121　(19-20)　2023/03/24
Publisher: Informa UK Limited
DOI： 10.1080/00268976.2023.2192836 　

ISSN： 0026-8976

eISSN： 1362-3028
Deep Learning to Reveal the Distribution and Diffusion of Water Molecules in Fuel Cell Catalyst Layers

Gaoyang Li, Yonghong Zhu, Yuting Guo, Takuya Mabuchi, Dong Li, Shengfeng Huang, Sirui Wang, Haiyi Sun, Takashi Tokumasu

ACS Applied Materials and Interfaces　15　(4)　5099-5108　2023/02/01

DOI： 10.1021/acsami.2c17198 　

ISSN： 1944-8244

eISSN： 1944-8252
Growth mechanism study of boron nitride atomic layer deposition by experiment and density functional theory

Naoya Uene, Takuya Mabuchi, Masaru Zaitsu, Yong Jin, Shigeo Yasuhara, Takashi Tokumasu

Computational Materials Science　217　2023/01/25

DOI： 10.1016/j.commatsci.2022.111919 　

ISSN： 0927-0256
Role of Gluex in the Ion Exchange Mechanism of CLC^F F⁻/H⁺ Antiporter

Akihiro Nakamura, Takashi Tokumasu, Takuya Mabuchi

Mechanisms and Machine Science　119　1-11　2023

DOI： 10.1007/978-3-031-02097-1_1 　

ISSN： 2211-0984

eISSN： 2211-0992
(Digital Presentation) A Coarse-Grained Molecular Dynamics Study on the Aggregation and Adsorption Behavior of Ionomer from Solution Onto Pt/C Substrate

Yuting Guo, Takuya Mabuchi, Gaoyang Li, Takashi Tokumasu

ECS Meeting Abstracts　2022/10/09

DOI： 10.1149/MA2022-02391365mtgabs 　
Carbon clusters on substrate surface for graphene growth- theoretical and experimental approach

Satoru Kaneko, Takashi Tokumasu, Manabu Yasui, Masahito Kurouchi, Satomi Tanaka, Chihiro Kato, Shigeo Yasuhara, Tamio Endo, Akifumi Matsuda, Mamoru Yoshimoto, Musa Can, Sumanta Kumar Sahoo, Kripasindhu Sardar, Jyh-Ming Ting, Masahiro Yoshimura

Scientific Reports　12　(1)　2022/09/22
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41598-022-20078-x 　

eISSN： 2045-2322

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Abstract Growth morphology of carbon clusters deposited on different substrates were investigated by theoretical and experimental approach. For theoretical approach, molecular dynamics was employed to evaluate an adsorptive stability of different size of carbon clusters placed on different substrates. The adsorptive stability was estimated by the difference of total energy of supercell designed as carbon cluster placed on a certain crystal plane of substrate. Among the simulations of this study, carbon cluster flatly settled down on the surface of SrTiO$$_{3}$$(001). The result was experimentally verified with layer by layer growth of graphene by pulsed laser deposition in carbon dioxide atmosphere. The absorptive stability can be useful reference for screening substrate for any target material other than graphene.
Crystal orientation of epitaxial oxide film on silicon substrate

Satoru Kaneko, Takashi Tokumasu, Manabu Yasui, Masahito Kurouchi, Shigeo Yasuhara, Tamio Endo, Masaki Azuma, Akufumi Matsuda, Mamoru Yoshimoto, Sumanta Kumar Sahoo, Kripasindhu Sardar, Jyh Ming Ting, Masahiro Yoshimura

Applied Surface Science　586　2022/06/01

DOI： 10.1016/j.apsusc.2022.152776 　

ISSN： 0169-4332
Prediction of nanoscale thermal transport and adsorption of liquid containing surfactant at solid–liquid interface via deep learning

Yuting Guo, Gaoyang Li, Takuya Mabuchi, Donatas Surblys, Taku Ohara, Takashi Tokumasu

Journal of Colloid and Interface Science　613　587-596　2022/05

DOI： 10.1016/j.jcis.2022.01.037 　

ISSN： 0021-9797

eISSN： 1095-7103
Prediction of the adsorption properties of liquid at solid surfaces with molecular scale surface roughness via encoding-decoding convolutional neural networks

Gaoyang Li, Yuting Guo, Takuya Mabuchi, Donatas Surblys, Taku Ohara, Takashi Tokumasu

Journal of Molecular Liquids　349　2022/03/01

DOI： 10.1016/j.molliq.2022.118489 　

ISSN： 0167-7322
Reactive force-field molecular dynamics simulation for the surface reaction of SiH<inf>x</inf> (x = 2–4) species on Si(1 0 0)-(2 × 1):H surfaces in chemical vapor deposition processes

Naoya Uene, Takuya Mabuchi, Masaru Zaitsu, Shigeo Yasuhara, Takashi Tokumasu

Computational Materials Science　204　2022/03

DOI： 10.1016/j.commatsci.2022.111193 　

ISSN： 0927-0256
Investigation of quantum effect of liquid hydrogen on homogeneous bubble nucleation using a density functional theory and molecular dynamics simulations

Ryuji Takahashi, Hiroki Nagashima, Takashi Tokumasu, Satoshi Watanabe, Shin ichi Tsuda

Fluid Phase Equilibria　553　2022/02/01

DOI： 10.1016/j.fluid.2021.113300 　

ISSN： 0378-3812
Molecular Dynamics Simulations of Cerium Ion Transport Phenomena in Polymer Electrolyte Membranes of Polymer Electrolyte Fuel Cells

Hiroto Suzuki, Takuya Mabuchi, Takashi Tokumasu

ECS Transactions　109　(9)　295-302　2022

DOI： 10.1149/10909.0295ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Molecular Dynamics Simulation of Scattering and Surface Diffusion of Oxygen Molecules on Ionomers in Catalyst Layers of PEFCs

Tomoki Hori, Takuya Mabuchi, Ikuya Kinefuchi, Takashi Tokumasu

ECS Transactions　109　(9)　95-101　2022

DOI： 10.1149/10909.0095ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Morphology Evolution and Adsorption Behavior of Ionomers from Solution to Pt/C Substrates

Yuting Guo, Takuya Mabuchi, Gaoyang Li, Takashi Tokumasu

Macromolecules　55　(11)　4245-4255　2022

DOI： 10.1021/acs.macromol.2c00533 　

ISSN： 0024-9297

eISSN： 1520-5835
Reactive Force-Field Molecular Dynamics Study of the Effect of Gaseous Species on SiliconGermanium Alloy Growth by PECVD Techniques

Naoya Uene, Takuya Mabuchi, Masaru Zaitsu, Shigeo Yasuhara, Takashi Tokumasu

International Conference on Simulation of Semiconductor Processes and Devices, SISPAD　2021-September　238-241　2021/09/27

DOI： 10.1109/SISPAD54002.2021.9592596 　
Molecular dynamics study of ion transport in polymer electrolytes of all-solid-state li-ion batteries Peer-reviewed

Takuya Mabuchi, Koki Nakajima, Takashi Tokumasu

Micromachines　12　(9)　1012　2021/09

DOI： 10.3390/mi12091012 　

eISSN： 2072-666X
Mesoscale morphologies of nafion-based blend membranes by dissipative particle dynamics Peer-reviewed

Unal Sen, Mehmet Ozdemir, Mustafa Erkartal, Alaattin Metin Kaya, Abdullah A. Manda, Ali Reza Oveisi, M. Ali Aboudzadeh, Takashi Tokumasu

Processes　9　(6)　984　2021/07

DOI： 10.3390/pr9060984 　

eISSN： 2227-9717
Influence of Ionomer Loading and Substrate Wettability on the Morphology of Ionomer Thin Films Using Coarse-Grained Solvent Evaporation Simulations Peer-reviewed

Takuya Mabuchi, Sheng Feng Huang, Takashi Tokumasu

Macromolecules　54　(1)　115-125　2021/01/12

DOI： 10.1021/acs.macromol.0c01303 　

ISSN： 0024-9297

eISSN： 1520-5835
Molecular Dynamics Study of Proton Conductivity at an Interface between Nafion and Graphene Sheet

Rikki Tanaka, Takuya Mabuchi, Yushi Zang, Bruce Hinds, Takashi Tokumasu

ECS Transactions　104　(8)　309-316　2021

DOI： 10.1149/10408.0309ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Analysis of the Effect of Surface Diffusion on Effective Diffusivity of Oxygen in Catalyst Layer by Direct Simulation Monte Carlo

Tomoki Hori, Takuya Mabuchi, Ikuya Kinefuchi, Takashi Tokumasu

ECS Transactions　104　(8)　371-376　2021

DOI： 10.1149/10408.0371ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Preface

Takashi Tokumasu, Hitomi Anzai, Koji Fujita, Kenichi Funamoto, Makoto Hirota, Hisashi Nakamura, Koji Shimoyama, Hidemasa Takana

JOURNAL OF FLUID SCIENCE AND TECHNOLOGY　16　(1)　2021

DOI： 10.1299/jfst.2021jfst0001 　

ISSN： 1880-5558
An evaluation of the self-diffusion coefficient of liquid hydrogen via the generic van der Waals equation of state and modified free volume theory Peer-reviewed

H. Nagashima, S. Tsuda, T. Tokumasu

Chemical Physics　539　110952-110952　2020/11/01
Publisher: Elsevier BV
DOI： 10.1016/j.chemphys.2020.110952 　

ISSN： 0301-0104
Ab initio studies of the effect of the fluorination on deprotonation reaction of the benzene sulfonic acid Peer-reviewed

Akinori Fukushima, Hironori Sakai, Takashi Tokumasu

JOURNAL OF MOLECULAR MODELING　26　(6)　2020/05

DOI： 10.1007/s00894-020-04402-8 　

ISSN： 1610-2940

eISSN： 0948-5023
Dispersion of Nafion lonomer Aggregates in 1-Propanol/Water Solutions: Effects of lonomer Concentration, Alcohol Content, and Salt Addition Peer-reviewed

Takuya Mabuchi, Sheng-Feng Huang, Takashi Tokumasu

MACROMOLECULES　53　(9)　3273-3283　2020/05

DOI： 10.1021/acs.macromol.9b02725 　

ISSN： 0024-9297

eISSN： 1520-5835
Nafion Ionomer Dispersion in Mixtures of 1-Propanol and Water Based on the Martini Coarse-Grained Model Peer-reviewed

Takuya Mabuchi, Sheng-Feng Huang, Takashi Tokumasu

JOURNAL OF POLYMER SCIENCE　58　(3)　487-499　2020/02

DOI： 10.1002/pol.20190101 　

ISSN： 2642-4150

eISSN： 2642-4169
Reactive force-field molecular dynamics study of sige thin film growth in plasma enhanced chemical vapor deposition processes Peer-reviewed

N. Uene, T. Mabuchi, M. Zaitsu, S. Yasuhara, T. Tokumasu

ECS Transactions　98　(5)　177-184　2020

DOI： 10.1149/09805.0177ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Multiscale simulation of proton transport in the catalyst layer with consideration of ionomer thickness distribution Peer-reviewed

T. Matsuda, K. Kobayashi, T. Mabuchi, G. Inoue, T. Tokumasu

ECS Transactions　98　(9)　187-196　2020

DOI： 10.1149/09809.0187ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Analysis of the influence of cerium ions on mass transport properties in polymer electrolyte membrane by molecular dynamics simulation Peer-reviewed

K. Ishikawa, T. Mabuchi, T. Tokumasu

ECS Transactions　98　(9)　439-446　2020

DOI： 10.1149/09809.0439ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Ionomer dispersion in dilute solution studied by coarse-grained molecular dynamics

Takuya Mabuchi, Takashi Tokumasu

INTERNATIONAL CONFERENCE ON TRENDS IN MATERIAL SCIENCE AND INVENTIVE MATERIALS: ICTMIM 2020　2020
Publisher: AIP Publishing
DOI： 10.1063/5.0013592 　
Reactive Force-Field Molecular Dynamics Study of the Silicon-Germanium Deposition Processes by Plasma Enhanced Chemical Vapor Deposition

Naoya Uene, Takuya Mabuchi, Masaru Zaitsu, Shigeo Yasuhara, Takashi Tokumasu

2020 INTERNATIONAL CONFERENCE ON SIMULATION OF SEMICONDUCTOR PROCESSES AND DEVICES (SISPAD 2020)　105-108　2020

ISSN： 1946-1569
Molecular Dynamics Analysis of Proton Diffusivity in Hydrated Nafion Membranes Contaminated with Ferrous Ions Peer-reviewed

Kiyoto Kawai, Takuya Mabuchi, Takashi Tokumasu

MACROMOLECULAR THEORY AND SIMULATIONS　29　(1)　2020/01

DOI： 10.1002/mats.201900047 　

ISSN： 1022-1344

eISSN： 1521-3919
Study of reflection models of gas molecules on water adsorbed surfaces in high-speed flows Peer-reviewed

Naoya Uene, Hideki Takeuchi, Yasutaka Hayamizu, Takashi Tokumasu

JOURNAL OF FLUID SCIENCE AND TECHNOLOGY　15　(1)　2020

DOI： 10.1299/jfst.2020jfst0005 　

ISSN： 1880-5558
Nucleation and Growth of Cavities in Hydrated Nafion Membranes under Tensile Strain: A Molecular Dynamics Study Peer-reviewed

William Goncalves, Takuya Mabuchi, Takashi Tokumasu

JOURNAL OF PHYSICAL CHEMISTRY C　123　(47)　28958-28968　2019/11

DOI： 10.1021/acs.jpcc.9b07101 　

ISSN： 1932-7447

eISSN： 1932-7455
Molecular Dynamics Study of Oxygen Diffusivity in Catalyst Layer International-journal Peer-reviewed

Masataka Nakauchi, Takuya Mabuchi, Yuta Yoshimoto, Toshihiro Kaneko, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

ECS Transactions　92　(8)　23-28　2019/10
Publisher: The Electrochemical Society (ECS)
DOI： 10.1149/09208.0023ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Molecular dyanamics simulation of thermal chemical vapor deposition for hydrogenated amorphous silicon on si (100) substrate by reactive force-field Peer-reviewed

Naoya Uene, Takuya Mabuchi, Masaru Zaitsu, Shigeo Yasuhara, Takashi Tokumasu

International Conference on Simulation of Semiconductor Processes and Devices, SISPAD　2019-September　2019/09

DOI： 10.1109/SISPAD.2019.8870438 　
Effects of water nanochannel diameter on proton transport in proton-exchange membranes Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS　57　(13)　867-878　2019/07

DOI： 10.1002/polb.24842 　

ISSN： 0887-6266

eISSN： 1099-0488
Molecular Dynamics Study of Oxygen Scattering Behavior on Perfluorosulfonic Acid Ionomer Thin Films Peer-reviewed

Masataka Nakauchi, Takuya Mabuchi, Yuta Yoshimoto, Takuma Hori, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

JOURNAL OF PHYSICAL CHEMISTRY C　123　(12)　7125-7133　2019/03

DOI： 10.1021/acs.jpcc.8b11475 　

ISSN： 1932-7447
Constriction of a lattice constant in an epitaxial magnesium oxide film deposited on a silicon substrate

Satoru Kaneko, Takashi Tokumasu, Yoshimi Nakamaru, Chiemi Kokubun, Kayoko Konda, Manabu Yasui, Masahito Kurouchi, Musa Can, Shalima Shawuti, Rieko Sudo, Tamio Endo, Shigeo Yasuhara, Akifumi Matsuda, Mamoru Yoshimoto

JAPANESE JOURNAL OF APPLIED PHYSICS　58　(SA)　2019/02

DOI： 10.7567/1347-4065/aaec11 　

ISSN： 0021-4922

eISSN： 1347-4065
Molecular dynamics study of oxygen transport resistance through ionomer thin film on Pt surface Peer-reviewed

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

JOURNAL OF POWER SOURCES　414　263-271　2019/02

DOI： 10.1016/j.jpowsour.2019.01.011 　

ISSN： 0378-7753

eISSN： 1873-2755
Preface

Takashi Tokumasu, Hitomi Anzai, Koji Fujita, Makoto Hirota, Hisashi Nakamura, Koji Shimoyama, Hidemasa Takana

JOURNAL OF FLUID SCIENCE AND TECHNOLOGY　14　(3)　2019

DOI： 10.1299/jfst.2019jfst0014 　

ISSN： 1880-5558
Nano/microscale simulation of proton transport in catalyst layer Peer-reviewed

K. Kobayashi, T. Mabuchi, G. Inoue, T. Tokumasu

ECS Transactions　92　(8)　515-522　2019

DOI： 10.1149/09208.0515ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Analysis of the influence of cerium ions on mass transport properties in polymer electrolyte membrane by molecular dynamics simulation Peer-reviewed

K. Ishikawa, T. Mabuchi, T. Tokumasu

ECS Transactions　92　(8)　421-428　2019

DOI： 10.1149/09208.0421ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Gas-Surface Dynamics of Oxygen Molecules on Nafion Ionomer Membrane Peer-reviewed

Masataka Nakauchi, Takuya Mabuchi, Takuma Hori, Yuta Yoshimoto, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

31ST INTERNATIONAL SYMPOSIUM ON RAREFIED GAS DYNAMICS (RGD31)　2132　170001　2019

DOI： 10.1063/1.5119654 　

ISSN： 0094-243X
Relationship between Proton Transport and Morphology of Perfluorosulfonic Acid Membranes: A Reactive Molecular Dynamics Approach Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

JOURNAL OF PHYSICAL CHEMISTRY B　122　(22)　5922-5932　2018/06

DOI： 10.1021/acs.jpcb.8b02318 　

ISSN： 1520-6106
Kinetic Analysis of Oxygen Transport Phenomena through Ionomer Thin Film on Pt Sueface in PEFC

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS AND ELECTROLYZERS 18 (PEFC&E 18)　86　(13)　489-496　2018

DOI： 10.1149/08613.0489ecst 　

ISSN： 1938-5862

eISSN： 1938-6737
Special Issue of the Fourteenth International Conference on Flow Dynamics (ICFD2017) Preface Peer-reviewed

Takashi Tokumasu, Makoto Hirota, Yuka Iga, Hisashi Nakamura, Koji Shimoyama, Hidemasa Takana

JOURNAL OF FLUID SCIENCE AND TECHNOLOGY　13　(4)　2018

DOI： 10.1299/jfst.2018jfst0022 　

ISSN： 1880-5558
Molecular Dynamics Study of the Thickness Dependence of Structure and Mass Transport in Ionomer Thin Film Peer-reviewed

Koichi Kobayashi, Takuya Mabuchi, Gen Inoue, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS AND ELECTROLYZERS 18 (PEFC&E 18)　86　(13)　469-474　2018

DOI： 10.1149/08613.0469ecst 　

ISSN： 1938-5862

eISSN： 1938-6737
Kinetic analysis of oxygen transport phenomena through ionomer thin film on Pt sueface in PEFC Peer-reviewed

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

ECS Transactions　86　(13)　489-496　2018

DOI： 10.1l49/086I3.0489ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Scattering Properties of Gas Molecules on Water Adsorbed Surfaces in High Knudsen Number Flows Peer-reviewed

Naoya Uene, Hideki Takeuchi, Yasutaka Hayamizu, Takashi Tokumasu

Proc. 21st Australasian Fluid Mechanics Conference　11C-5　2018
Validation of Classica Mixing Rule Coupled with a Van der Waals-type Equation of State for Supercritical Mixture System of Oxygen and Hydrogen using Molecular Simulation Peer-reviewed

Ryuji Takahashi, Nobuyuki Tsuboi, Takashi Tokumasu, Shin-ichi Tsuda

Mechanical Engineering Letters　4　18-00369　2018
Theoretical study of high performance hydrocarbon-based ion-exchange membranes Peer-reviewed

Akinori Fukushima, Hironori Sakai, Takashi Tokumasu

COMPUTATIONAL AND THEORETICAL CHEMISTRY　1121　44-48　2017/12

DOI： 10.1016/j.comptc.2017.10.008 　

ISSN： 2210-271X

eISSN： 1872-7999
An Analysis of Quantum Effect on the Proton Conduction in BaZrO3Membrane

Hiroki Nagashima, Takashi Tokumasu

ECS Transactions　80　(9)　119-126　2017/08/31
Publisher: The Electrochemical Society
DOI： 10.1149/08009.0119ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
A molecular dynamics study of nuclear quantum effect on diffusivity of hydrogen molecule Peer-reviewed

H. Nagashima, S. Tsuda, N. Tsuboi, A. K. Hayashi, T. Tokumasu

JOURNAL OF CHEMICAL PHYSICS　147　(2)　24501　2017/07

DOI： 10.1063/1.4991732 　

ISSN： 0021-9606

eISSN： 1089-7690
Modeling of local gas transport in catalyst layers of PEM fuel cells Peer-reviewed

Tetsuya Mashio, Hiroshi Iden, Atsushi Ohma, Takashi Tokumasu

JOURNAL OF ELECTROANALYTICAL CHEMISTRY　790　27-39　2017/04

DOI： 10.1016/j.jelechem.2017.02.045 　

ISSN： 1572-6657

eISSN： 1873-2569
Special Issue of the Thirteenth International Conference on Flow Dynamics (ICFD2016) Preface Peer-reviewed

Tomohide Niimi, Yuka Iga, Hisashi Nakamura, Koji Shimoyama, Hidemasa Takana, Takashi Tokumasu

JOURNAL OF FLUID SCIENCE AND TECHNOLOGY　12　(3)　2017

DOI： 10.1299/jfst.2017jfst0020 　

ISSN： 1880-5558
Exploring the performance of dual-phase oxygen transport membranes for carbon capture purposes Peer-reviewed

Ryan Falkenstein-Smith, Matthew Rushby, Hiroki Nagashima, Takashi Tokumasu, Jeongmin Ahn

JOURNAL OF FLUID SCIENCE AND TECHNOLOGY　12　(3)　17-00430　2017

DOI： 10.1299/jfst.2017jfst0028 　

ISSN： 1880-5558
Dependence of electroosmosis on polymer structure in proton exchange membranes Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

MECHANICAL ENGINEERING JOURNAL　4　(5)　17-00054　2017

DOI： 10.1299/mej.17-00054 　

ISSN： 2187-9745
Molecular Analysis of Structural Effect of Ionomer on Oxygen Permeation Properties in PEFC Peer-reviewed

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

JOURNAL OF THE ELECTROCHEMICAL SOCIETY　164　(6)　F628-F637　2017

DOI： 10.1149/2.1301706jes 　

ISSN： 0013-4651

eISSN： 1945-7111
Molecular Dynamics Study of Ionomer Dispersions in Water/Alcohol Mixtures Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

Extended Abstracts of the Ninth JSME-KSME Thermal and Fluids Engineering Conference,　TFEC9　(1653)　2017
Channel Size Dependence of the Friction Force around the Contact Line Region Peer-reviewed

Akinori Fukushima, Takashi Tokumasu

Extended Abstracts of the Ninth JSME-KSME Thermal and Fluids Engineering Conference　TFEC9　(1473)　2017
Validation of Classical Mixing Rule Coupled with a Cubic Equation of State for the Thermodynamic Properties in Oxygen – Hydrogen Mixture System Peer-reviewed

Ryuji Takahashi, Nobuyuki Tsuboi, Takashi Tokumasu, Shin-ichi Tsuda

Extended Abstracts of the Ninth JSME-KSME Thermal and Fluids Engineering Conference　TFEC9　(1422)　2017
A Discussion on the Effect of Quantum Nature of Liquid Hydrogen on its Bubble Nucleation Using Density Functional Theory Peer-reviewed

Daiki Yasui, Hiroki Nagashima, Takashi Tokumasu, Satoshi Watanabe, Shin-ichi Tsuda

Extended Abstracts of the Ninth JSME-KSME Thermal and Fluids Engineering Conference　TFEC9　(1349)　2017
Molecular Analysis of Oxygen Permeation Properties in Ionomer on Pt Surface on PEMFC Peer-reviewed

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

Proc. of 6th European PEFC and Electrolyser Forum　B0807　2017
Molecular Simulations of Oxygen Scattering and Surface Diffusion on Ionomer Surface Peer-reviewed

Masataka Nakauchi, Takuya Mabuchi, Takuma Hori, Yuta Yoshimoto, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

Proc. of 6th European PEFC and Electrolyser Forum　B0804　2017
Ionomer dispersions in water/alcohol solutions by coarse-grained molecular dynamics Peer-reviewed

T. Mabuchi, T. Tokumasu

ECS Transactions　80　(8)　577-581　2017

DOI： 10.1149/08008.0577ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
Gas-surface interaction study of oxygen molecules on ionomer surface in catalyst layer Peer-reviewed

M. Nakauchi, T. Mabuchi, T. Hori, Y. Yoshimoto, I. Kinefuchi, H. Takeuchi, T. Tokumasu

ECS Transactions　80　(8)　197-203　2017

DOI： 10.1149/08008.0197ecst 　

ISSN： 1938-6737

eISSN： 1938-5862
A study on pressure-driven gas transport in porous media: from nanoscale to microscale Peer-reviewed

Yoshiaki Kawagoe, Tomoya Oshima, Ko Tomarikawa, Takashi Tokumasu, Tetsuya Koido, Shigeru Yonemura

MICROFLUIDICS AND NANOFLUIDICS　20　(12)　162　2016/12

DOI： 10.1007/s10404-016-1829-8 　

ISSN： 1613-4982

eISSN： 1613-4990
Dynamics of oxygen scattering on ionomer surface in catalyst layer of PEFC Peer-reviewed

Masataka Nakauchi, Takuya Mabuchi, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

2016 IEEE 16th International Conference on Nanotechnology (IEEE-NANO)　218-221　2016/11

DOI： 10.1109/NANO.2016.7751557 　
Molecular Dynamics Study of Ionomer Adsorption at a Carbon Surface in Catalyst Ink Peer-reviewed

Tetsuya Mashio, Atsushi Ohma, Takashi Tokumasu

ELECTROCHIMICA ACTA　202　14-23　2016/06

DOI： 10.1016/j.electacta.2016.04.004 　

ISSN： 0013-4686

eISSN： 1873-3859
Analysis of the oxygen scattering behaviour on ionomer surface in catalyst layer of PEFC Peer-reviewed

Masataka Nakauchi, Takuya Mabuchi, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

Renewable Energy and Power Quality Journal　1　(14)　349-352　2016/05

DOI： 10.24084/repqj14.315 　

eISSN： 2172-038X
Special Issue of the Eleventh International Conference on Flow Dynamics (ICFD2014) Preface

Takehiko Sato, Yuji Hattori, Tomohide Niimi, Hidemasa Takana, Takashi Tokumasu

JOURNAL OF FLUID SCIENCE AND TECHNOLOGY　11　(1)　2016

DOI： 10.1299/jfst.2016jfst0001 　

ISSN： 1880-5558
Numerical Analysis of Nanostructure around Ferrous ion in Hydrated Nafion Membrane Peer-reviewed

Kiyoto Kawai, Takuya Mabuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 16 (PEFC 16)　75　(14)　695-701　2016

DOI： 10.1149/07514.0695ecst 　

ISSN： 1938-5862
Analysis of the oxygen scattering behaviour on ionomer surface in catalyst layer of PEFC Peer-reviewed

Masataka Nakauchi, Takuya Mabuchi, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

Renewable Energy & Power Quality Journal, European Association for the Development of Renewable energies, Environment and Power Quality　3　315　2016
Scattering Dynamics of Oxygen Molecules on Nafion Membrane Peer-reviewed

Masataka Nakauchi, Takuya Mabuchi, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

30TH INTERNATIONAL SYMPOSIUM ON RAREFIED GAS DYNAMICS (RGD 30)　1786　100004　2016

DOI： 10.1063/1.4967615 　

ISSN： 0094-243X
Special Issue of the Twelfth International Conference on Flow Dynamics (ICFD2015) Preface Peer-reviewed

Hideya Nishiyama, Yuji Hattori, Yuka Iga, Hidemasa Takana, Takashi Tokumasu, Shigeru Yonemura

JOURNAL OF FLUID SCIENCE AND TECHNOLOGY　11　(4)　JFST0020-1　2016

DOI： 10.1299/jfst.2016jfst0020 　

ISSN： 1880-5558
Molecular dynamics study of the effect of wettability of the carbon support on proton transport in Nafion ionomer thin films Peer-reviewed

Joji Aochi, Takuya Mabuchi, Takashi Tokumasu

JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY　11　(3)　16-00423　2016

DOI： 10.1299/jtst.2016jtst0045 　

ISSN： 1880-5566
PEFCカソード触媒層のプロトン輸送に関する分子論的研究 Peer-reviewed

青地成二, 馬渕拓哉, 徳増崇

燃料電池　15　(3)　78-84　2016
Publisher:
ISSN： 1346-6623
A Molecular Dynamics Study of Transport Properties in Degraded Nafion Membranes Peer-reviewed

S. Kono, T. Mabuchi, T. Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 16 (PEFC 16)　75　(14)　651-657　2016

DOI： 10.1149/07514.0651ecst 　

ISSN： 1938-5862
Effect of Water Cluster Structure on Proton Transport in Proton-Exchange Membranes Using Reactive Molecular Dynamics Simulations Peer-reviewed

T. Mabuchi, T. Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 16 (PEFC 16)　75　(14)　631-636　2016

DOI： 10.1149/07514.0631ecst 　

ISSN： 1938-5862
Reflection Characteristics of Oxygen Molecule on Ionomer Surface Peer-reviewed

M. Nakauchi, T. Mabuchi, I. Kinefuchi, H. Takeuchi, T. Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 16 (PEFC 16)　75　(14)　615-621　2016

DOI： 10.1149/07514.0615ecst 　

ISSN： 1938-5862
Molecular Dynamics Study on Proton Transport in Supported Nafion Ionomer Thin Films on Lennard-Jones Walls Peer-reviewed

Joji Aochi, Takuya Mabuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 16 (PEFC 16)　75　(14)　607-614　2016

DOI： 10.1149/07514.0607ecst 　

ISSN： 1938-5862
Molecular Dynamics Simulation of Oxygen Diffusivity, Solubility, and Permeability in Ionomer on Pt Surface Peer-reviewed

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 16 (PEFC 16)　75　(14)　129-137　2016

DOI： 10.1149/07514.0129ecst 　

ISSN： 1938-5862
Molecular Dynamics Simulation of Channel Size Dependence of the Friction Coefficient between a Water Droplet and a Nanochannel Wall Peer-reviewed

Akinori Fukushima, Toshiki Mima, Ikuya Kinefuchi, Takashi Tokumasu

JOURNAL OF PHYSICAL CHEMISTRY C　119　(51)　28396-28404　2015/12

DOI： 10.1021/acs.jpcc.5b07951 　

ISSN： 1932-7447
Modeling of Pressure-driven Gas Flow in Nanoscale Porous Media

Yoshiaki Kawagoe, Shigeru Yonemura, Takashi Tokumasu

Proceedings of ICFD2015　834-835　2015/10/28
Molecular Dynamics Mechanism of Quantum Effect on the Thermodynamic and Transport Properties of Hydrogen

Hiroki Nagashima, Shin-ichi Tsuda, Nobuyuki Tsuboi, A. Koichi Hayashi, Takashi Tokumasu

Proceedings of ICFD2015　430-431　2015/10/28
Analysis of Nanoscale Transport Phenomena of Reaction Materials for Next Generation PEFC Invited

Takashi Tokumasu

Proceedings of ICFD2015　2015/10/27
A modified two-state empirical valence bond model for proton transport in aqueous solutions Peer-reviewed

Takuya Mabuchi, Akinori Fukushima, Takashi Tokumasu

JOURNAL OF CHEMICAL PHYSICS　143　(1)　2015/07

DOI： 10.1063/1.4926394 　

ISSN： 0021-9606

eISSN： 1089-7690
Effect of Structure of Nafion and Hydrocarbon Ionomer on Oxygen Solubility Peer-reviewed

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

Proceednigs of 5th European PEFC & H2 Forum, European Fuel Cell Conference　2015/07
Quantum chemical analysis of the deprotonation of sulfonic acid in a hydrocarbon membrane model at low hydration levels Peer-reviewed

Hironori Sakai, Takashi Tokumasu

SOLID STATE IONICS　274　94-99　2015/06

DOI： 10.1016/j.ssi.2015.03.005 　

ISSN： 0167-2738

eISSN： 1872-7689
Extraction of the Density Fluctuations in Diatomic Fluids Around the Critical Points Using Molecular Dynamics Simulation Peer-reviewed

Shin-Ichi Tsuda, Masato Tomi, Nobuyuki Tsuboi, Shohei Ikawa, Takashi Tokumasu

JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY　15　(4)　3117-3120　2015/04

DOI： 10.1166/jnn.2015.9623 　

ISSN： 1533-4880

eISSN： 1533-4899
Molecular Dynamics Simulation of Proton Transport in Polymer Electrolyte Membrane Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY　15　(4)　2958-2963　2015/04

DOI： 10.1166/jnn.2015.9647 　

ISSN： 1533-4880

eISSN： 1533-4899
Molecular Dynamics Study for Channel Size Dependence of Shear Stress Between Droplet and Wall Peer-reviewed

Akinori Fukushima, Toshiki Mima, Ikuya Kinefuchi, Takashi Tokumasu

JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY　15　(4)　3224-3228　2015/04

DOI： 10.1166/jnn.2015.9686 　

ISSN： 1533-4880

eISSN： 1533-4899
Molecular simulation of oxygen solubility and diffusivity in ionomer on Pt surface Peer-reviewed

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

ECS Transactions　69　(17)　691-699　2015
Publisher: Electrochemical Society Inc.
DOI： 10.1149/06917.0691ecst 　

ISSN： 1938-6737 1938-5862
Effects of water structure on proton transport in nafion thin films with molecular dynamics simulations Peer-reviewed

Joji Aochi, Takuya Mabuchi, Takashi Tokumasu

ECS Transactions　69　(17)　715-721　2015
Publisher: Electrochemical Society Inc.
DOI： 10.1149/06917.0715ecst 　

ISSN： 1938-6737 1938-5862
Molecular dynamics study of proton transport in modeled water cluster structure of polymer electrolyte membrane Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

ECS Transactions　69　(17)　723-729　2015
Publisher: Electrochemical Society Inc.
DOI： 10.1149/06917.0723ecst 　

ISSN： 1938-6737 1938-5862
Molecular simulation of proton conductivity in nafion membrane contaminated with ferrous ion Peer-reviewed

Kiyoto Kawai, Takuya Mabuchi, Takashi Tokumasu

ECS Transactions　69　(17)　579-586　2015
Publisher: Electrochemical Society Inc.
DOI： 10.1149/06917.0579ecst 　

ISSN： 1938-6737 1938-5862
Expansion of lattice constants of aluminum nitride thin film prepared on sapphire substrate by ECR plasma sputtering method Peer-reviewed

Satoru Kaneko, Hironori Torii, Takao Amazawa, Takeshi Ito, Manabu Yasui, Masahito Kurouchi, Akinori Fukushima, Takashi Tokumasu, Seughwan Lee, Sungkyun Park, Hirofumi Takikawa, Mamoru Yoshimoto

JAPANESE JOURNAL OF APPLIED PHYSICS　53　(11)　2014/11

DOI： 10.7567/JJAP.53.11RA11 　

ISSN： 0021-4922

eISSN： 1347-4065
Effects of polytetrafluoroethylene treatment and compression on gas diffusion layer microstructure using high-resolution X-ray computed tomography Peer-reviewed

Navvab Khajeh-Hosseini-Dalasm, Takashi Sasabe, Takashi Tokumasu, Ugur Pasaogullari

JOURNAL OF POWER SOURCES　266　213-221　2014/11

DOI： 10.1016/j.jpowsour.2014.05.004 　

ISSN： 0378-7753

eISSN： 1873-2755
A Study on Nanoscale Gas Transport in Porous Media

Yoshiaki Kawagoe, Tomoya Oshima, Shigeru Yonemura, Takashi Tokumasu

Proceedings of the Eleventh International Conference on Flow Dynamics　446-447　2014/10/08
aEffect of bound state of water on hydronium ion mobility in hydrated Nafion using molecular dynamics simulations Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

JOURNAL OF CHEMICAL PHYSICS　141　(10)　2014/09

DOI： 10.1063/1.4894813 　

ISSN： 0021-9606

eISSN： 1089-7690
Preface

SATO Takehiko, HATTORI Yuji, NIIMI Tomohide, TAKANA Hidemasa, TOKUMASU Takashi

JFST　9　(5)　JFST0067-JFST0067　2014
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jfst.2014jfst0067 　

ISSN： 1880-5558
Quantum chemical analysis about deprotonation reaction of sulfonic group of modeled hydrocarbon membrane in low hydration level Peer-reviewed

H. Sakai, T. Tokumasu

ECS Transactions　64　(3)　433-439　2014
Publisher: Electrochemical Society Inc.
DOI： 10.1149/06403.0433ecst 　

ISSN： 1938-6737 1938-5862
EFFECTS OF COMPRESSION ON GDL MICROSTRUCTURE BY HIGH-RESOLUTION X-RAY COMPUTED TOMOGRAPHY Peer-reviewed

Navvab Khajeh D. Hosseini, Takashi Sasabe, Takashi Tokumasu, Ugur Pasaogullari

PROCEEDINGS OF THE ASME 11TH FUEL CELL SCIENCE, ENGINEERING, AND TECHNOLOGY CONFERENCE, 2013　2014

DOI： 10.1115/FuelCell2013-18405 　
An Improved EVB Model for Proton Transport in Polymer Electrolyte Membrane Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 14　64　(3)　699-704　2014

DOI： 10.1149/06403.0699ecst 　

ISSN： 1938-5862
A Molecular Dynamics Study of Nuclear Quantum Effect on the Diffusion of Hydrogen in Condensed Phase Peer-reviewed

Hiroki Nagashima, Shin-ichi Tsuda, Nobuyuki Tsuboi, Mitsuo Koshi, A. Koichi Hayashi, Takashi Tokumasu

INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014)　1618　950-953　2014

DOI： 10.1063/1.4897890 　

ISSN： 0094-243X
Atomistic Study of Proton Hopping Mechanism in Hydrated Nation Membrane Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

2014 IEEE INTERNATIONAL NANOELECTRONICS CONFERENCE (INEC)　2014

ISSN： 2159-3523
Numerical Analysis of Proton Conductivity in Hydrated Nafion Membrane Contaminated with Iron Ion Peer-reviewed

Kiyoto Kawai, Takuya Mabuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 14　64　(3)　789-792　2014

DOI： 10.1149/06403.0789ecst 　

ISSN： 1938-5862
Reaction Analysis for Deprotonation of the Sulfonic Group of Perfluorosulfonic Acid Molecules at Low Hydration Levels Peer-reviewed

Hironori Sakai, Takashi Tokumasu

JOURNAL OF PHYSICAL CHEMISTRY A　118　(1)　275-282　2014/01

DOI： 10.1021/jp409781s 　

ISSN： 1089-5639

eISSN： 1520-5215
Molecular Simulation of Oxygen Permeation through Ionomer in Catalyst Layer Peer-reviewed

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 14　64　(3)　559-565　2014

DOI： 10.1149/06403.0559ecst 　

ISSN： 1938-5862
An analysis of the quantum effect on the thermodynamic and transport properties of cryogenic hydrogen using molecular dynamics method

Hiroki Nagashima, Shin-ichi Tsuda, Nobuyuki Tsuboi, Mitsuo Koshi, A. Koichi Hayashi, Takashi Tokumasu

2ND INTERNATIONAL CONFERENCE ON MATHEMATICAL MODELING IN PHYSICAL SCIENCES 2013 (IC-MSQUARE 2013)　490　(1)　2014

DOI： 10.1088/1742-6596/490/1/012160 　

ISSN： 1742-6588
二原子分子流体の臨界点近傍におけるゆらぎ構造の分子動力学計算

冨正人, 井川祥平, 坪井伸幸, 徳増崇, 津田伸一

日本機械学会論文集　80　(816)　2014

DOI： 10.1299/transjsme.2014tep0231 　
An Analysis of Quantum Effects on the Thermodynamic Properties of Cryogenic Hydrogen using the Path Integral Method Peer-reviewed

H. Nagashima, S. Tsuda, N. Tsuboi, M. Koshi, A.K. Hayashi, T. Tokumasu

J. Chem. Phys.　140　134506-1-134506-10　2014

DOI： 10.1063/1.4870036 　
Direct Simulation Monte Carlo Analysis of Gas Transport in Microporous Structure Based on X-ray Computed Tomography Peer-reviewed

Ikuya Kinefuchi, Junpei Oyama, Koji Yokoyama, Norio Kubo, Takashi Tokumasu, Yoichiro Matsumoto

ECS Transactions　58　(1)　71-78　2013/10

DOI： 10.1149/05801.0071ecst 　
Bottom-up construction of interaction models of non-Markovian dissipative particle dynamics Peer-reviewed

Yuta Yoshimoto, Ikuya Kinefuchi, Toshiki Mima, Akinori Fukushima, Takashi Tokumasu, Shu Takagi

PHYSICAL REVIEW E　88　(4)　043305　2013/10

DOI： 10.1103/PhysRevE.88.043305 　

ISSN： 1539-3755

eISSN： 1550-2376
Proton-conducting blend membranes of Nafion/poly(vinylphosphonic acid) for proton exchange membrane fuel cells Peer-reviewed

Unal Sen, Oktay Acar, Sevim Unugur Celik, Ayhan Bozkurt, Ali Ata, Takashi Tokumasu, Akira Miyamoto

JOURNAL OF POLYMER RESEARCH　20　(9)　2013/09

DOI： 10.1007/s10965-013-0217-2 　

ISSN： 1022-9760
A molecular dynamics study of a nanoscale liquid bridge under shear Peer-reviewed

Takashi Tokumasu, Marie-Helene Meurisse, Nicolas Fillot, Philippe Vergne

TRIBOLOGY INTERNATIONAL　59　10-16　2013/03

DOI： 10.1016/j.triboint.2012.08.009 　

ISSN： 0301-679X

eISSN： 1879-2464
A molecular dynamics study for momentum transport phenomena in nanoscale liquid bridge

Takashi Tokumasu, Marie-Hélène Meurisse, Nicolas Fillot, Philippe Vergne

5th World Tribology Congress, WTC 2013　2　1733-1735　2013
Publisher: Politecnico di Torino (DIMEAS)
Quantum chemical analysis about deprotonation reaction of sulfonic group of perfluorosulfonic acid species in the low hydration level Peer-reviewed

H. Sakai, T. Tokumasu

ECS Transactions　58　(1)　1145-1151　2013
Publisher: Electrochemical Society Inc.
DOI： 10.1149/05801.1145ecst 　

ISSN： 1938-6737 1938-5862
MOLECULAR DYNAMICS STUDY OF PROTON AND WATER TRANSPORT IN NAFION MEMBRANE Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

PROCEEDINGS OF THE 11TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS, AND MINICHANNELS, 2013　2013

DOI： 10.1115/ICNMM2013-73084 　
Molecular analysis of proton and water transport in the nanostructure of polymer electrolyte membrane Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B　79　(807)　2446-2455　2013
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.79.2446 　

ISSN： 0387-5016
An analysis of quantum effect on the p-V-T relation of cryogenic hydrogen using centroid molecular dynamics method Peer-reviewed

Hiroki Nagashima, Shinichi Tsuda, Nobuyuki Tsuboi, Mitsuo Koshi, A. Koichi Hayashi, Takashi Tokumasu

Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B　79　(805)　1848-1857　2013

DOI： 10.1299/kikaib.79.1848 　

ISSN： 0387-5016
Molecular Dynamics Study of Oxygen Permeation of Ionomer of Hydrocarbon Peer-reviewed

Yuta Sugaya, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 13 (PEFC 13)　58　(1)　1165-1174　2013

DOI： 10.1149/05801.1165ecst 　

ISSN： 1938-5862
A MOLECULAR DYNAMICS ANALYSIS OF QUANTUM EFFECT ON THE THERMODYNAMIC PROPERTIES OF LIQUID HYDROGEN Peer-reviewed

Hiroki Nagashima, Shin-ichi Tsuda, Nobuyuki Tsuboi, Mitsuo Koshi, A. Koichi Hayashi, Takashi Tokumasu

PROCEEDINGS OF THE 11TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS, AND MINICHANNELS, 2013　2013
A Revised EVB Model for Proton Transport in Hydrated Nafion Membrane Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 13 (PEFC 13)　58　(1)　261-269　2013

DOI： 10.1149/05801.0261ecst 　

ISSN： 1938-5862
An Analysis of Quantum Effect on the p-V-T Relation of Cryogenic Hydrogen Using Centroid Molecular Dynamics Method

NAGASHIMA HIROKI, TSUDA SHIN'ICHI, TSUBOI NOBUYUKI, KOSHI MITSUO, HAYASHI KOICHI, TOKUMASU TAKASHI

日本機械学会論文集 B編(Web)　79　(805)　1848-1857 (WEB ONLY)-1857　2013
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.79.1848 　

ISSN： 1884-8346

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In this paper, we conducted analysis of p-V-T relation of cryogenic hydrogen using classical Molecular Dynamics (MD) and path integral Centroid MD (CMD) method to understand an effect of quantum nature of hydrogen molecules. We performed NVE constant MD simulation across a wide density-temperature region to obtain an Equation Of State (EOS). Simulation results were compared with experimental data. As a result, it was confirmed that classical MD cannot reproduce the experimental data at the high density region. On the other hand, CMD well reproduces the thermodynamic properties of liquid hydrogen. Moreover, it was clarified that taking the quantum effect into account makes repulsion force larger and the potential well smaller. Because of this mechanism, the intermolecular interaction of hydrogen diminishes and the virial pressure increases.
Molecular dynamics study for the friction coefficient between a water droplet and a solid wall Peer-reviewed

Akinori Fukushima, Toshiki Mima, Ikuya Kinefuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 13 (PEFC 13)　58　(1)　87-93　2013

DOI： 10.1149/05801.0087ecst 　

ISSN： 1938-5862
Large-scale Molecular Dynamics Simulations for Analyses of Transport Phenomena in Polymer Electrolyte Fuel Cell Peer-reviewed

Takashi Tokumasu, Akinori Fukushima, Takuya Mabuchi, Yuta Sugaya

Journal of Computational Chemistry, Japan　12　(1)　8-15　2013
Publisher: Society of Computer Chemistry, Japan
DOI： 10.2477/jccj.2012-0021 　

ISSN： 1347-1767

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Computer simulation is a very powerful tool to analyze transport phenomena in the membrane electrode assembly (MEA) of polymer electrolyte fuel cells (PEFCs). In particular, there are many nanoscale structures in this flow field, and therefore the phenomena should be analyzed from the microscopic point of view rather than computational fluid dynamics. In this paper, we report large-scale molecular dynamics (MD) simulations to analyze these flows. In particular, dissociation phenomena of a hydrogen molecule on a Pt catalyst, transport phenomena of proton and water in a polymer electrolyte membrane (PEM), oxygen permeability of ionomers in a catalyst layer (CL), and transport phenomena of a water droplet in a nanopore were simulated, and their characteristics are discussed. In the analysis of the dissociation phenomena of the hydrogen molecule, it was found that the trend of dissociation probability as a function of impinging energy considering the motion of the molecule differs from that without considering the motion of the molecule. In the analysis of proton transfer in a PEM, the diffusion coefficients obtained by this simulation were consistent with the experimental data. In the analysis of oxygen permeability of ionomers, the dependence of water content on the permeability was estimated and the difference between ionomer on catalyst layer and that in bulk state was clarified. In the analysis of transport phenomena of a water droplet in a nanopore, we compared the results of our simulation with the macroscopic governing equation.
A Study for Transport Phenomena of Nanoscale Gas Flow in Porous Media

Tomoya Oshima, Shigeru Yonemura, Takashi Tokumasu

Proceedings of the Ninth International Conference on Flow Dynamics　662-663　2012/09/21
A Molecular Dynamics Study for Dissociation of H-2 Molecule on Pt(111) Surface Peer-reviewed

Takashi Tokumasu

MANAGEMENT, MANUFACTURING AND MATERIALS ENGINEERING, PTS 1 AND 2　452-453　1144-1148　2012

DOI： 10.4028/www.scientific.net/AMR.452-453.1144 　

ISSN： 1022-6680
MOLECULAR DYNAMICS STUDY OF OXYGEN PERMEATION THROUGH THE IONOMER OF PEFC CATALYST LAYER Peer-reviewed

Kiminori Sakai, Takashi Tokumasu

FLUID MEASUREMENTS AND INSTRUMENTATION CAVITATION AND MULTIPHASE FLOW ADVANCES IN FLUIDS ENGINEERING EDUCATION MICROFLUIDICS, VOL 2　349-352　2012
A MOLECULAR DYNAMICS STUDY FOR THE CHARACTERISTICS OF PROTON TRANSFER IN POLYMER ELECTROLYTE MEMBRANE Peer-reviewed

Takashi Tokumasu, Taiki Yoshida

FLUID MEASUREMENTS AND INSTRUMENTATION CAVITATION AND MULTIPHASE FLOW ADVANCES IN FLUIDS ENGINEERING EDUCATION MICROFLUIDICS, VOL 2　353-357　2012
A Numerical Study for Transport Phenomena of Nanoscale Gas Flow in Porous Media Peer-reviewed

Tomoya Oshima, Shigeru Yonemura, Takashi Tokumasu

28TH INTERNATIONAL SYMPOSIUM ON RAREFIED GAS DYNAMICS 2012, VOLS. 1 AND 2　1501　809-815　2012

DOI： 10.1063/1.4769625 　

ISSN： 0094-243X
AN ESTIMATION OF THERMODYNAMIC AND TRANSPORT PROPERTIES OF CRYOGENIC HYDROGEN USING CLASSICAL MOLECULAR SIMULATION Peer-reviewed

Hiroki Nagashima, Takashi Tokumasu, Shin-ichi Tsuda, Nobuyuki Tsuboi, Mitsuo Koshi, A. Koichi Hayashi

FLUID MEASUREMENTS AND INSTRUMENTATION CAVITATION AND MULTIPHASE FLOW ADVANCES IN FLUIDS ENGINEERING EDUCATION MICROFLUIDICS, VOL 2　289-299　2012

DOI： 10.1115/AJK2011-36005 　
MOLECULAR DYNAMICS STUDY OF OXYGEN PERMEATION THROUGH THE IONOMER OF PEFC CATALYST LAYER Peer-reviewed

Kiminori Sakai, Takashi Tokumasu

FLUID MEASUREMENTS AND INSTRUMENTATION CAVITATION AND MULTIPHASE FLOW ADVANCES IN FLUIDS ENGINEERING EDUCATION MICROFLUIDICS, VOL 2　2　349-352　2012

DOI： 10.1115/AJK2011-36020 　
PROTON TRANSFER IN POLYMER ELECTROLYTE MEMBRANE BY MOLECULAR DYNAMICS METHOD Peer-reviewed

Takashi Tokumasu

PROCEEDINGS OF THE ASME 9TH INTERNATIONAL CONFERENCE ON FUEL CELL SCIENCE, ENGINEERING, AND TECHNOLOGY 2011　869-873　2012

DOI： 10.1115/FuelCell2011-54963 　
Limits of classical molecular simulation on the estimation of thermodynamic properties of cryogenic hydrogen Peer-reviewed

Hiroki Nagashima, Takashi Tokumasu, Shin-ichi Tsuda, Nobuyuki Tsuboi, Mitsuo Koshi, A. Koichi Hayashi

MOLECULAR SIMULATION　38　(5)　404-413　2012

DOI： 10.1080/08927022.2010.548383 　

ISSN： 0892-7022

eISSN： 1029-0435
Molecular dynamics study of water transport property in micro hydrophobic pore Peer-reviewed

Akinori Fukushima, Toshiki Mima, Ikuya Kinefuchi, Takashi Tokumasu

ECS Transactions　50　(2)　197-206　2012

DOI： 10.1149/05002.0197ecst 　

ISSN： 1938-5862 1938-6737
Molecular simulation of proton and water transport in hydrated nafion membrane Peer-reviewed

T. Mabuchi, T. Tokumasu

ECS Transactions　50　(2)　175-181　2012

DOI： 10.1149/05002.0175ecst 　

ISSN： 1938-5862 1938-6737
Investigation on effect of PTFE treatment on GDL micro-structure by high-resolution X-ray CT Peer-reviewed

T. Sasabe, G. Inoue, S. Tsushima, S. Hirai, T. Tokumasu, U. Pasaogullari

ECS Transactions　50　(2)　735-744　2012

DOI： 10.1149/05002.0735ecst 　

ISSN： 1938-5862 1938-6737
Nanoscale transport phenomena in PEM of PEFC by large scale molecular dynamics simulations Invited Peer-reviewed

T. Tokumasu

ECS Transactions　50　(2)　859-868　2012

DOI： 10.1149/05002.0859ecst 　

ISSN： 1938-5862 1938-6737
A Molecular Dynamics Study of Momentum Transport in a Nanoscale Liquid Bridge

Takashi Tokumasu, Marie-Helene Meurisse, Nicolas Fillot, Philippe Vergne

Proceedings of the Eleventh International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　138-139　2011/11/10
A molecular Dynamics study on the Thermodynamic Estimation of Cryogenic Hydrogen

Hiroki Nagashima, Takashi Tokumasu, Shin-ichi Tsuda, Nobuyuki Tsuboi, Mitsuo Koshi, A. Koichi Hayashi

Proceedings of the Eleventh International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　136-137　2011/11
A Molecular Dynamics Study for the Lubrication Phenomena of Nanoscale Liquid Bridge

Takashi Tokumasu, Marie-Helene Meurisse, Nicolas Fillot, Philippe Vergne

ITC Hiroshima 2011 Extended Abstract　2011/11/01
Energy dissipation in non-isothermal molecular dynamics simulations of confined liquids under shear Peer-reviewed

Hassan Berro, Nicolas Fillot, Philippe Vergne, Takashi Tokumasu, Taku Ohara, Gota Kikugawa

JOURNAL OF CHEMICAL PHYSICS　135　(13)　2011/10

DOI： 10.1063/1.3644938 　

ISSN： 0021-9606
Molecular dynamics study of the effects of translational energy and incident angle on dissociation probability of hydrogen/deuterium molecules on Pt(111) Peer-reviewed

Tetsuya Koido, Ko Tomarikawa, Shigeru Yonemura, Takashi Tokumasu

JOURNAL OF APPLIED PHYSICS　110　(2)　2011/07

DOI： 10.1063/1.3606434 　

ISSN： 0021-8979

eISSN： 1089-7550
The dynamic effects on dissociation probability of H-2-Pt(111) system by embedded atom method Peer-reviewed

Takashi Tokumasu, Daigo Ito

JOURNAL OF APPLIED PHYSICS　109　(6)　2011/03

DOI： 10.1063/1.3554690 　

ISSN： 0021-8979

eISSN： 1089-7550
Numerical Analysis of Gas Flow in Porous Media with Surface Reaction Peer-reviewed

Ko Tomarikawa, Shigeru Yonemura, Takashi Tokumasu, Tetsuya Koido

27TH INTERNATIONAL SYMPOSIUM ON RAREFIED GAS DYNAMICS, 2010, PTS ONE AND TWO　1333　796-+　2011

DOI： 10.1063/1.3562744 　

ISSN： 0094-243X
Modeling of the Dissociative Adsorption Probability of the H-2-Pt(111) System Based on Molecular Dynamics Peer-reviewed

Tetsuya Koido, Ko Tomarikawa, Shigeru Yonemura, Takashi Tokumasu

27TH INTERNATIONAL SYMPOSIUM ON RAREFIED GAS DYNAMICS, 2010, PTS ONE AND TWO　1333　469-+　2011

DOI： 10.1063/1.3562692 　

ISSN： 0094-243X
A DFT Study of Bond Dissociation Trends of Perfluorosulfonic Acid Membrane Peer-reviewed

T. Tokumasu, I. Ogawa, M. Koyama, T. Ishimoto, A. Miyamoto

JOURNAL OF THE ELECTROCHEMICAL SOCIETY　158　(2)　B175-B179　2011

DOI： 10.1149/1.3518421 　

ISSN： 0013-4651
A Molecular Dynamics Study of the Effect of the Incidence Angle on the Dissociation Probability of H-2 on Pt(111) Peer-reviewed

Tetsuya Koido, Daigo Ito, Takashi Tokumasu, Ko Tomarikawa, Shigeru Yonemura

JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY　6　(3)　333-343　2011

DOI： 10.1299/jtst.6.333 　

ISSN： 1880-5566
Analysis of Proton and Water Transfer in PFSA Membrane by Molecular Dynamics Simulation Peer-reviewed

Takuya Mabuchi, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 11　41　(1)　2115-2123　2011

DOI： 10.1149/1.3635742 　

ISSN： 1938-5862

eISSN： 1938-6737
Development of the new model for the proton hopping by molecular dynamics simulation

Hironori Sakai, Taiki Yoshida, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 11　41　(1)　2097-2103　2011

DOI： 10.1149/1.3635740 　

ISSN： 1938-5862

eISSN： 1938-6737
Molecular Dynamics Study of Oxygen Permeation in the PFSA Ionomer on Pt Catalyst Surface Peer-reviewed

Kiminori Sakai, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 11　41　(1)　2105-2113　2011

DOI： 10.1149/1.3635741 　

ISSN： 1938-5862

eISSN： 1938-6737
Molecular Dynamics Study of Oxygen Permeation in the PFSA Ionomer on Pt Catalyst Surface

Kiminori Sakai, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 11　41　(1)　2105-2113　2011

DOI： 10.1149/1.3635741 　

ISSN： 1938-5862

eISSN： 1938-6737
A MOLECULAR DYNAMICS STUDY FOR DIFFUSIVITY OF PROTON IN POLYMER ELECTROLYTE MEMBRANE

Takashi Tokumasu, Taiki Yoshida

PROCEEDINGS OF THE ASME/JSME 8TH THERMAL ENGINEERING JOINT CONFERENCE 2011, VOL 3　485-+　2011
A Molecular Dynamics Study on the Thermodynamic Properties of Croygenic Hydrogen

H. Nagashima, T. Tokumasu, S. Tsuda, N. Tsuboi, A. Koichi Hayashi

Proceedings of the 10th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　112-113　2010/11/02
Assesment of Different Thermostating Techniques in the Simulation of Molecular Lubrication

H. Berro, T. Tokumasu, T. Ohara, G. Kikugawa, N. Fillot, P. Vergne

Proceedings of the 10th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　128-129　2010/11/02
Analysis of Proton Transferring Property including Grotthus Mechanism in Polymer Electrolyte Membrane

Taiki Yoshida, Takashi Tokumasu

Proceedings of the Seventh International Conference on Flow Dynamics　380-381　2010/11
Molecular dynamics study of oxygen permeation to catalytic metal covered with polyelectrolyte membrane

Kiminori Sakai, Takashi Tokumasu

Proceedings of the Seventh International Conference on Flow Dynamics　384-385　2010/11
Proton transport in hydrogen bond network of confined water

Nobuya Miyoshi, Ikuya Kinefuchi, Takashi Tokumasu, Shu Takagi, Yoichiro Matsumoto

Proceedings of the 10th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　108-109　2010/11
Transport phenomena of water droplet in a slit pore

Yoshinobu Hamada, Takashi Tokumasu

Porceedings of the seventh International Conference on Flow Dynamics　382-383　2010/11
Dissociation Probality of Gas Molecule on Metal Surface Including Dynamic Effects

Takashi Tokumasu

Proceedings of 13th International Conference on Theoretical Aspects of Catalysis　119-119　2010/06/23
Molecular dynamics study of transport phenomena of water droplet in a nano slit pore

Yoshinobu Hamada, Takashi Tokumasu

Proceedings of 13th International Conference on Theoretical Aspects of Catalysis　118-118　2010/06/23
Proton Transfer Including Grotthus Mechanism in Polyelectrolyte Membrane by Molecular Dynamics Simulation

Taiki Yoshida, Takashi Tokumasu

Proceedings of 13th International Conference on Theoretical Aspects of Catalysis　50-50　2010/06/22
A molecular dynamics study for the dissociation phenomena of gas molecule on metal surface Peer-reviewed

Takashi Tokumasuy, Daigo Ito

e-Journal of Surface Science and Nanotechnology　8　211-216　2010/05/08

DOI： 10.1380/ejssnt.2010.211 　

ISSN： 1348-0391
T0501-1-5 Molecular Analysis of Momentum Transport Phenomena in a Nanoscale Liquid Bridge

Tokumasu Takashi, Berro Hassan, Meurisse Marie-Helene, Fillot Nicolas, Vergne Philippe

The proceedings of the JSME annual meeting　2010　77-78　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2010.8.0_77 　

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In this research the momentum transport phenomena in a nanoscale liquid bridge were simulated by Molecular Dynamics method and its nanoscale characteristics were analyzed. Water was assumed as the lubricant. Momentum flux was generated in a liquid bridge by controlling the velocity of a part of the liquid bridge. Using the velocity gradient of the liquid bridge and the momentum flux, viscosity coefficients of the liquid bridge were obtained. We analyze the dependence of the width of the liquid bridge on the viscosity coefficient and the differences of the viscosity coefficients between liquid bridges and bulk water were confirmed.
T0501-2-2 Analysis of Proton Transferring Property in Polyelectrolyte Membrane by Molecular Dynamics Simulation

Yoshida Taiki, Tokumasu Takashi

The proceedings of the JSME annual meeting　2010　83-84　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2010.8.0_83 　

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This study describes the property of proton transfer in Nafion membrane analyzed by molecular dynamics (MD) simulation including both Vehicle and Grotthus mechanism. To treat Grotthus mechanism, Empirical Valence Bond(EVE) method was introduced to MD simulation. The potential energy barrier of proton hopping obtained by EVB method was adjusted to the computational result of Density Functional Theory (DFT). After adjusting EVB potential, it is confirmed that protons hop along the hydrogen bond network consecutively. The parameter for the simulation of Nafion membrane was water contents λ, which is defined as the ratio of water molecules and hydronium ions to sulfo groups, SO_<3^->, obtained by λ=N_<H2O,H3O+>/N_<SO3->. The changes of transferring properties and structure of molecules with the changes of λ were analyzed by Mean Square Displacement and Radial Distribution Function, respectively.
T0501-2-3 Dissociative Adsorption Probability Model of the H_2-Pt(111) System Based on Molecular Dynamics

KOIDO Tetsuya, TOMARIKAWA Ko, YONEMURA Shigeru, TOKUMASU Takashi

The proceedings of the JSME annual meeting　2010　85-86　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2010.8.0_85 　

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Molecular Dynamics (MD) was used to simulate dissociative adsorption of hydrogen molecule on Pt(1l1) surface considering the movement of the surface atoms and gas molecules. Embedded Atom Method (EAM) was applied to represent the interaction potential. A number of MD simulations of gas molecules impinging on Pt(111) surface were carried out changing initial orientations, incident azimuth angles, and impinging positions on the surface using uniform random numbers with fixed initial translational energy, initial rotational energy, and incident polar angle. The number of incidents that dissociated gas molecules was counted to compute dissociation probability. The dissociation probability was analyzed and expressed by a mathematical function of initial conditions of impinging molecule, namely translational energy, rotational energy, and incident polar angle. And the model was verified by comparing with MD simulation results of molecular beam experiments.
T0501-3-3 Numerical Analysis of Gas Flow in Porous Media

TOMARIKAWA Ko, YONEMURA Shigeru, TOKUMASU Takashi, KOIDO Tetsuya

The proceedings of the JSME annual meeting　2010　97-98　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2010.8.0_97 　

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Gas flow with surface reaction in porous media appears in various regions of engineering. In porous media with holes as small as a molecular mean free path, i. e., Knudsen number Kn of gas flow in the narrow channel is in the order of unity. Therefore, the direct simulation Monte Carlo (DSMC) method is suitable to solve transport phenomena in porous media. We perform 2D DSMC simulations of such a flow. Porous media are modeled as an aggregation of randomly-placed spherical particles. The shape of narrow channel in porous media is complicated. To reduce complexity, we propose the simplification for porous structures, i. e., we simplify solid bodies in porous media as aggregations of cubes or as aggregations of polyhedra. We perform simulations with and without simplification. We compare results and investigate effects of the simplification.
T0501-1-4 Transport phenomena of water droplet in a nano slit pore

HAMADA Yoshinobu, TOKUMASU Takashi

The proceedings of the JSME annual meeting　2010　75-76　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2010.8.0_75 　

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In this research, we reported the dependence of pore size on the characteristics of transport phenomena of confined water in a nano slit pore by molecular dynamics (MD) simulation. The two surfaces were made of graphite, whose distance was set at 15, 30, and 60 A. The interaction potential between water and carbon was Lennard-Jones potential, and that between water molecules was SPC/E. The water formed a film in each system. The film moved when constant fictitious force parallel to the walls was given to water molecules in the pore. From the results, we examined dependence on width of the velocity of water in the slit pores.
T0501-2-5 The Effect of Intermolecular Potential Model on Thermodynamic Properties of Cryogenic Hydrogen

NAGASHIMA Hiroki, TOKUMASU Takashi, TSUDA Shinichi, TSUBOI Nobuyuki, HAYASHI A.Koichi

The proceedings of the JSME annual meeting　2010　89-90　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2010.8.0_89 　

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In this paper, we investigated the effect of intermolecular potential model on thermodynamic properties of cryogenic hydrogen. We applied three empirical potential models and one ab-initio potential which was derived by Molecular Orbital (MO) calculation. We performed NVE constant Molecular Dynamics (MD) calculation to obtain Equation Of State (EOS). Calculation results were compared with NIST data using the principle of corresponding date. As a result, it was confirmed that every potential showed the same tendency and cannot reproduce NIST data at the high density region.
A Molecular Dynamics Study of the Effect of Incident Angle on Dissociation Probability of H-2/D-2 - Pt(111) System Peer-reviewed

Tetsuya Koido, Daigo Ito, Takashi Tokumasu, Kou Tomarikawa, Shigeru Yonemura

ELECTROCHEMISTRY: SYMPOSIUM ON INTERFACIAL ELECTROCHEMISTRY IN HONOR OF BRIAN E. CONWAY　25　(23)　59-68　2010

DOI： 10.1149/1.3328511 　

ISSN： 1938-5862

eISSN： 1938-6737
A molecular dynamics study of the effect of incident angle on dissociation probability of H2/D2 - Pt(111) system

Tetsuya Koido, Daigo Ito, Takashi Tokumasu, Kou Tomarikawa, Shigeru Yonemura

ECS Transactions　25　(23)　59-68　2010

DOI： 10.1149/1.3328511 　

ISSN： 1938-5862 1938-6737
Reliability of Classical Molecular Dynamics Method to Thermodynamic Properties of Hydrogen Peer-reviewed

Hiroki Nagashima, Takashi Tokumasu, Shin-ichi Tsuda, Nobuyuki Tsuboi, A. Koichi Hayashi

Proceedings of 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition　2010/01
Effect of motion of atoms or molecules on dissociation probability of a hydrogen molecule on a platinum surface (2nd Report, analysis of dynamic effect at various sites of pt surface) Peer-reviewed

Takashi Tokumasu, Daigo Ito

Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B　76　(762)　334-341　2010
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.76.762_334 　

ISSN： 0387-5016
Effect of motion of atoms or molecules on dissociation probability of a hydrogen molecule on a platinum surface (1st report, improvement of EAM potential and its verification) Peer-reviewed

Takashi Tokumasu, Daigo Ito

Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B　76　(764)　667-674　2010
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.76.764_667 　

ISSN： 0387-5016
Molecular Dynamics Study of Proton Transfer including Grotthus Mechanism in Polymer Electrolyte Membrane Peer-reviewed

Taiki Yoshida, Takashi Tokumasu

POLYMER ELECTROLYTE FUEL CELLS 10, PTS 1 AND 2　33　(1)　1055-+　2010

DOI： 10.1149/1.3484599 　

ISSN： 1938-5862

eISSN： 1938-6737
A Molecular Study on the Thermodynamic and Transport Properties of Liquid Hydrogen

H. Nagashima, T. Tokumasu, S. Tsuda, N. Tsuboi, K. A. Hayashi

Proc. of the Ninth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　96-97　2009/11/05
Molecular Dynamics Study about Lubrication Phenomena of Liquid Bridges

Takashi Tokumasu, Marie-Helene Meurisse, Nicolas Fillot, Philippe Vergne

Proc. of the Ninth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　88-89　2009/11/05
Molecular Simulation of Nanoscale Flow in Polymer Electrolyte Fuel Cell

Takashi Tokumasu

Proc. of the Sixth International Conference on Flow Dynamics　580　2009/11/05
Lubrication Phenomena of Nanoscale Liquid Bridges by Molecular Dynamics Method

akashi Tokumasu, Marie-Helene Meurisse, Nicolas Fillot, Philippe Vergne

Proc. of the World Tribology Congress 2009　620　2009/09/10
The Effect of Different Thermostating Techniques on Friction and Dissipation in Molecular Dynamics Simulations of Confined Lubrication Films

Hassan Berro, Nicoas Fillot, Philippe Vergne, Takashi Tokumasu, Taku Ohara, Gota Kikugawa

Proc. of the World Tribology Congress 2009　622　2009/09/10
T0501-2-1 Proton Transfer in Polyelectrolyte Membrane by Molecular Dynamics Simulation

Yoshida T., Tokumasu T.

The proceedings of the JSME annual meeting　2009　107-108　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2009.8.0_107 　

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Protons transfer in polyelectrolyte membrane by both Vehicle and Grotthus mechanism. Due to the Grotthus mechanism, protons transfer at higher velocity in water. The mechanism, however, hasn't been widely considered in studies about proton transfer in polyelectrolyte membrane by molecular dynamics (MD) because of its complexity, whereas Vehicle mechanism has been done. This paper describes proton transfer behavior in Nafion as a polyelectrolyte membrane by MD simulation including both Vehicle and Grotthus mechanism. To treat Grotthus mechanism, Empirical Valence Bond (EVB) method is used. The potential energy barrier of proton hopping obtained by EVB method is adjusted to the computational result of Density Functional Theory (DFT). The structure of water and Nafion molecules is analyzed by Radial Distribution Function (RDF). Diffusion coefficient of proton is analyzed by Mean Square Displacement (MSD).
T0501-2-6 A Molecular Study of Dissociation Phenomena of Hydrogen Molecule on Platinum Surface

TOKUMASU Takashi, ITO Daigo

The proceedings of the JSME annual meeting　2009　117-118　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2009.8.0_117 　

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Dissociation process of hydrogen molecule on platinum surface was simulated by Molecular Dynamics method. EAM potential was used as an interaction between a hydrogen molecule and a platinum surface. Firstly a dissociation probability against translational energy was obtained using the potential without considering the motion of atoms. Another dissociation probability was obtained by the Molecular Dynamics simulation and they were compared with each other to analyze the effect of the motion of atoms on the dissociation probability. The results showed that the tendency of the dissociation probability is different depending on the dissociation site, for instance, top, bridge and fee site.
T0501-3-1 A Study of Correlation between Thermophysical Properties of Low Temperature Hydrogen and its Intermolecular Potential

NAGASHIMA Hiroki, TOKUMASU Takashi, TSUDA Shinichi, TSUBOI Nobuyuki, HAYASHI A.Koichi

The proceedings of the JSME annual meeting　2009　119-120　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2009.8.0_119 　

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In this study the correlation between thermophysical properties of low temperature hydrogen and its intermolecular potential was investigated by classical molecular dynamics method (MD). Lennard-Jones (LJ) potential, 2-Center Lennard-Jones (2CLJ) potential and modified Buckingham (exp-6) potential were applied for this calculation. MD simulations were performed at a wide density-temperature range. Equation of state (EOS) was obtained based on the MD results, and they were compared with NIST (National Institute of Standards and Technology) data. As a result, it was confirmed that the thermal properties obtained by MD results can reproduce the NIST data at gas phase, while it cannot at liquid phase and around its critical point. This distinction are considered to arisee from the many-body effect or quantum effect of real hydrogen liquid.
A Modeling of Thermal Properties of Hydrogen/Oxygen System Using Molecular Simulations Peer-reviewed

Shin-ichi Tsuda, Nobuhiro Yamanishi, Takashi Tokumasu, Nobuyuki Tsuboi, Yoichiro Matsumoto

Proc. of 47th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition　2009/01
A DFT Study for the Durability of Perfluorosulfonic Acid Membrane Peer-reviewed

T. Tokumasu, I. Ogawa, M. Koyoma, T. Ishimoto, A. Miyamoto

PROTON EXCHANGE MEMBRANE FUEL CELLS 9　25　(1)　765-772　2009

DOI： 10.1149/1.3210628 　

ISSN： 1938-5862
Molecular Dynamics study on dissociation probability of H2 on Pt(111) surface

Daigo Ito, Takashi Tokumasu

Proceedings of the Eighth International Symposium on Advanced Fluid Information and Transdisplinary Fluid Integration　44-45　2008/12
Molecular study about dissociation phenomena of H2 on Pt surface

Daigo Ito, Takashi Tokumasu

Proceedings of Fifth International Conference on Flow Dyanmics　OS8-53　2008/11
金属表面上の気体分子の解離吸着現象に関する分子動力学的解析 Peer-reviewed

徳増崇, 原香菜子, 伊藤大吾

日本機械学会論文集B編　74　(739)　684-691　2008/03
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.74.684 　

ISSN： 0387-5016

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Dissociation phenomena of gas molecule on metal surface was analyzed by Molecular Dynamics Method. Platinum (111) surface and hydrogen were chosen to be the metal surface and the gas molecule, respectively. Embedded Atom Method was used as the interaction between the surface and the atoms in order to express the dependence of electron density. The parameters were determined so that the results such as the electron density, adsorption energy of an H atom on a Pt(111) surface and the interaction between H atoms of an H_2 molecule obtained by EAM method were consistent with that obtained by Density Functional Theory or empirical function. Collisions of a hydrogen molecule with a Platinum surface were simulated by Molecular Dynamics method and the dissociation probability was obtained. Using the results, effect of motion of the surface atoms or the hydrogen molecule on the dissociation probability was analyzed.
508 Molecular Dynamics study about dissociation probability of H_2 molecule on Pt surface

ITO Daigo, TOKUMASU Takashi

The proceedings of the JSME annual meeting　2008　215-216　2008
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2008.8.0_215 　

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Dissociative adsorption phenomena of hydrogen molecule on platinum surface was simulated by the Molecular Dynamics Method. The Embedded Atom Method (EAM) was used as an interaction potential between an H_2 molecule and a Pt surface in order to reproduce the dissociation barrier which the molecule has to pass over to dissociate on the surface. The functions of the EAM were adjusted so that they can describe the orders of dissociation barriers at some dissociation sites on a Pt(111) surface calculated by the Density functional theory (DFT). Many cases of collision of an H_2 molecule with a Pt(111) surface were simulated and dissociation probability was obtained. Using the results, the dependence of dissociation probability on dissociation barrier at some dissociation sites on a Pt(111) surface was analyzed.
Molecular dynamics study for dissociation phenomena of a gas molecule on a metal surface Peer-reviewed

Takashi Tokumasu, Kanako Hara, Daigo Ito

Heat Transfer - Asian Research　37　(8)　485-498　2008

DOI： 10.1002/htj.20222 　

ISSN： 1099-2871 1523-1496
Numerical Analysis for the Characteristics of Heat and Fluid Flow Against the Pattern of Channel in PEFC Peer-reviewed

Kohji Imuta, Takashi Tokumasu

Proc. of the Seventh International Symposium on Advanced Fluid Information and the Fource International Symposium on Transdisciplinary Fluid Integration　228-229　2007/12
Proton Transfer in Polyelectrolyte Membrane by Molecular Dynamics Simulation Peer-reviewed

Satoshi Ito, Takashi Tokumasu

Proc. of the Seventh International Symposium on Advanced Fluid Information and the Fource International Symposium on Transdisciplinary Fluid Integration　230-231　2007/12
Molecular Dynamics Study About Dissociation Phenomena of H2 on Pt(111) Surface Peer-reviewed

Daigo Ito, Takashi Tokumasu

Proc. of the Seventh International Symposium on Advanced Fluid Information and the Fource International Symposium on Transdisciplinary Fluid Integration　304-305　2007/12
PEFC電極触媒表面の気体分子の解離確率に関する数値シミュレーション Peer-reviewed

徳増崇, 伊藤大吾

第14回燃料電池シンポジウム講演予稿集　247-248　2007/12
Thermodynamic effect on a cavitating inducer in liquid nitrogen Peer-reviewed

Yoshiki Yoshida, Kengo Kikuta, Satoshi Hasegawa, Mitsuru Shimagaki, Takashi Tokumasu

JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME　129　(3)　273-278　2007/03

DOI： 10.1115/1.2427076 　

ISSN： 0098-2202

eISSN： 1528-901X
The Effect of the Motion of Surface Atoms on the Dissociative Adsorption of Hydrogen Molecule Peer-reviewed

Takashi Tokumasu

Proc. Japan NANO 2007　164-165　2007/02
気体分子の解離確率に対する分子の熱運動の影響 Peer-reviewed

徳増崇, 伊藤大吾

第44回日本伝熱シンポジウム講演予稿集　(3)　589-590　2007
分子動力学法による白金表面上の水素分子解離現象の解析 Peer-reviewed

徳増崇, 伊藤大吾

流体工学部門講演会講演概要集　214　2007
The dependence of molecular motion on the dissociative adsorption of H-2 on Pt(111) Peer-reviewed

Takashi Tokumasu, Daigo Ito

PROCEEDINGS OF THE ASME/JSME THERMAL ENGINEERING SUMMER HEAT TRANSFER CONFERENCE 2007, VOL 1　47-51　2007
Thermal conductivity of diatomic liquid in a narrow channel including a nanobubble Peer-reviewed

Takashi Tokumasu

FLUID DYNAMICS RESEARCH　38　(11)　761-771　2006/11

DOI： 10.1016/j.fluiddyn.2006.05.003 　

ISSN： 0169-5983
Dissociation Phenomena of H2 on Pt(111) Surface

Takashi Tokumasu

Proceedings of the Third International Conference on Flow Dynamics　67-68　2006/11
Dissociation Probability of H2 on Pt Surface

Takashi Tokumasu, Kanako Hara, Katsuhide Ohira

Proceedings of the Third International Symposium on Transdisciplinary Fluid Integration　61-62　2006/06
Dissociative Adsorption of H2 on the Electrode Catalyst of Fuel Cell

Takashi Tokumasu, Kanako Hara, Katsuhide Ohira

Proceedings of Japan NANO 2006　128-129　2006/02
キャビテーションの熱力学的効果に対するレイノルズ数の影響

徳増崇, 関野夕美子, 上條謙二郎

第55回理論応用力学講演会講演論文集　2006

DOI： 10.11345/japannctam.55.0.37.0 　
白金表面における水素分子解離吸着現象に関する分子動力学的解析

徳増崇, 原香菜子, 大平勝秀

第13回燃料電池シンポジウム講演予稿集　305-308　2006
白金表面における水素分子の解離吸着

徳増崇, 大平勝秀

日本流体力学会年会2006　2006　295-295　2006
Publisher:

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The dissociative adsorption of H_2 on Pt surface is studied by molecular dynamics (MD) simulation using Embedded Atom Method (EAM). The parameters or functions of this method are determined based on the results of Density Functional Theory (DFT). The dissociation barrier of each orientation of molecule obtained by EAM is analyzed and compared with that obtained by DFT. Many cases of collision of a H_2 molecule on Pt surface are simulated and dissociation probability is obtained. Consequently, dissociation probability changes greatly by the thermal motion of surface atoms. Moreover, the effect of translational and rotational energy of molecule on the dissociation probability is analyzed.
液体窒素中のインデューサに発生するキャビテーションの熱力学的効果 Peer-reviewed

吉田義樹, 菊田研吾, 長谷川敏, 島垣満, 中村憲明, 徳増崇

日本機械学会論文集B編　72　(713)　54-60　2006/01
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.72.54 　

ISSN： 0387-5016

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For experimental investigations of the thermodynamic effect on a cavitating inducer, it is neccesary to observe the cavitation. However, visualizations of the cavitation are not so easy in cryogenic flow. For this reason, we estimated the cavity region in liquid nitrogen based on measurements of the pressure fluctuation near the blade tip. The degree of the thermodynamic effect was found to increase with the increase of the cavity length of the tip cavitation. The estimated temperature depression caused by vaporization increased rapidly when the cavity length extended over the throat. In addition, the estimated temperature inside the bubble nearly reached the temperature of the triple point when the pump performance deteriorated.
液体窒素キャビテーション流動の基礎特性に対する流体温度の影響 Peer-reviewed

新井山一樹, 尾池守, 徳増崇, 上條謙二郎

日本機械学会論文集B編　72　(713)　46-53　2006/01

DOI： 10.1299/kikaib.72.46 　
A molecular dynamics study of bubble nucleation in liquid oxygen with impurities Peer-reviewed

Shin-Ichi Tsuda, Takashi Tokumasu, Kenjiro Kamijo

Heat Transfer - Asian Research　34　(7)　514-526　2005/11

DOI： 10.1002/htj.20082 　

ISSN： 1099-2871
Quantum molecular dynamics simulation of dissociative adsorption of H-2/Pt(111) Peer-reviewed

T Tokumasu, K Kamijo, A Miyamoto

Rarefied Gas Dynamics　762　1031-1036　2005

DOI： 10.1063/1.1941670 　

ISSN： 0094-243X
Thermodynamic effect on a cavitating inducer in liquid nitrogen Peer-reviewed

Yoshiki Yoshida, Kengo Kikuta, Satoshi Hasegawa, Mitsuru Shimagaki, Noriaki Nakamura, Takashi Tokumasu

PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER CONFERENCE, VOL 2　591-596　2005

DOI： 10.1115/FEDSM2005-77430 　

ISSN： 1093-4928
燃料電池電極触媒上での水素分子の挙動に関する分子動力学的解析

原香菜子, 徳増崇, 大平勝秀

日本流体力学会年会2005　2005　98-98　2005
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The dissociation mechanism of H_2 on Pt(111) surface is studied by molecular dynamics (MD) simulation using embedded-atom method (EAM). First, we investigate the precision of the EAM by comparing some results, such as potential energy surface (PES), of the EAM calculation with those of density functional theory (DFT) calculation. The PES by the EAM calculation is in reasonable agreement with DFT calculation. Using this EAM potential, the dissociation process of H_2 on Pt(111) surface is simulated. The dissociation probability in the case that surface atoms are fixed is higher than the probability in the case that surface atoms are moved.
Molecular dynamics study of bubble nucleation in liquid oxygen including impurities Peer-reviewed

Shinichi Tsuda, Takashi Tokumasu, Kenjiro Kamijo

Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B　71　(701)　200-207　2005
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.71.200 　

ISSN： 0387-5016
Inverse phenomenon of nucleation rate in binary liquid-gas mixtures (molecular dynamics study of molecular diameter dependence on the inverse phenomenon) Peer-reviewed

Shinichi Tsuda, Takashi Tokumasu, Shu Takagi, Yoichiro Matsumoto

Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B　71　(707)　1893-1900　2005
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.71.1893 　

ISSN： 0387-5016
Dynamic response analysis of high-pressure rocket pumps Invited Peer-reviewed

SI Jun, T Tokumasu, K Kamijo

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES　47　(157)　181-188　2004/11

DOI： 10.2322/tjsass.47.181 　

ISSN： 0549-3811
The numerical analysis of the effect of flow properties on the thermodynamic effect of cavitation Invited Peer-reviewed

T Tokumasu, Y Sekino, K Kamijo

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES　47　(156)　146-152　2004/08

DOI： 10.2322/tjsass.47.146 　

ISSN： 0549-3811
Molecular dynamics study for the thermal conductivity of diatomic liquid Invited Peer-reviewed

T Tokumasu, K Kamijo

SUPERLATTICES AND MICROSTRUCTURES　35　(3-6)　217-225　2004/03

DOI： 10.1016/j.spmi.2003.11.003 　

ISSN： 0749-6036
高圧液体水素供給系の動的挙動の解析 Peer-reviewed

全相仁, 徳増崇, 上條謙二郎

ターボ機械　31　(8)　459-466　2004
Publisher: Turbomachinery Society of Japan
DOI： 10.11458/tsj1973.31.459 　

ISSN： 0385-8839

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Effect of compressibility of liquid hydrogen on dynamic response of a high pressure LH₂ turbopump system including pipes has been analyzed. Simulation results of a nonlinear compressible mathematical model have been compared with those of a nonlinear incompressible mathematical model. Design parameters of LE-7 engine were used to simulate steady state condition and the boundary condition of tank pressure as well as pump outlet pressure was controlled to simulate unsteady condition. Effects of dynamic characteristics parameters of a cavitating inducer such as cavitation compliance and mass flow gain factor on dynamic response of a compressible flow system were analyzed as well.
水平配管内に設置された収縮拡大円管に於ける低温流体キャビテーション流れの観察

新井山一樹, 尾池守, 徳増崇, 上條謙二郎

日本航空宇宙学会北部支部2004年講演会および第5回再使用型宇宙推進系シンポジウム講演論文集　77-82　2004
Pt表面上の水素吸着に関する量子・分子動力学的解析

徳増崇, 上條謙二郎, 宮本明

日本流体力学会年会2004講演論文集, 2004　2004　290-291　2004
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The adsorption phenomena of H_2 on Pt (111) surface were simulated by the combination of accelerated Quantum Molecular Dynamics (QMD) method and classical Molecular Dynamics (MD) method. About QMD method, only the valence orbitals were considered and a Hamiltonian matrix and an overlap integral matrix were approximated to the analytical function of the distance between the atoms. It was confirmed that the probability density function of electron obtained by this method is very consistent with the results of Density Functional Theory (DFT). About the binding energy of Pt bulk and the partial density of state (PDOS), the results obtained by this method were qualitatively consistent with each other. On the viewpoint of energy conservation and temperature control, it was confirmed that this method can simulate the reaction phenomena on the catalyst well.
金属表面における解離吸着現象の量子・分子動力学的解析

徳増崇, 大平勝秀, 宮本明

熱工学コンファレンス講演論文集　147-148　2004
圧力変動計測による極低温インデューサに発生するキャビテーションの観察

菊田研吾, 長谷川敏, 島垣満, 中村憲明, 徳増崇, 吉田義樹

第82期流体工学部門講演会講演論文集(CD-ROM)　128　2004
Dynamic Response Analysis of a High Pressure LH2 Feed System Peer-reviewed

Sang-In JUN, Takashi TOKUMASU, Kenjiro KAMIJO

Turbomachinery　31　(8)　459-466　2003/08
Publisher: Turbomachinery Society of Japan
DOI： 10.11458/tsj1973.31.459 　

ISSN： 0385-8839

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Effect of compressibility of liquid hydrogen on dynamic response of a high pressure LH₂ turbopump system including pipes has been analyzed. Simulation results of a nonlinear compressible mathematical model have been compared with those of a nonlinear incompressible mathematical model. Design parameters of LE-7 engine were used to simulate steady state condition and the boundary condition of tank pressure as well as pump outlet pressure was controlled to simulate unsteady condition. Effects of dynamic characteristics parameters of a cavitating inducer such as cavitation compliance and mass flow gain factor on dynamic response of a compressible flow system were analyzed as well.
Effect of molecular elongation on the thermal conductivity of diatomic liquids Peer-reviewed

T Tokumasu, T Ohara, K Kamijo

JOURNAL OF CHEMICAL PHYSICS　118　(8)　3677-3685　2003/02

DOI： 10.1063/1.1540089 　

ISSN： 0021-9606
Dynamic Molecular Collision (DMC) model for general diatomic rarefied gas flows Peer-reviewed

T Tokumasu, Y Matsumoto, K Kamijo

RAREFIED GAS DYNAMICS　663　312-319　2003

ISSN： 0094-243X
Dynamic Response Analysis of High Pressure Rocket Pumps Peer-reviewed

Sang-In Jun, Takashi Tokumasu, Kenjiro Kamijo

CAV2003　OS-4-007　2003
A New Modeling of Sheet Cavitation Considering the Thermodynamic Effects Peer-reviewed

Takashi Tokumasu, Yumiko Sekino, Kenjiro Kamijo

CAV2003　GS-16-003　2003
Cavitating Flow of Liquid Nitrogen in Horizontal Rectangular Nozzle Peer-reviewed

Jun Ishimoto, Masahiro Onishi, Takashi Tokumasu, Kenjiro Kamijo

IMECE'03　IMECE2003-41250　2003
Observations of Cryogenic Two-Phase Flow

Kazuki NIIYAMA, Mamoru OIKE, Takashi TOKUMASU, Kenjiro Kamijo

AFI-2003　65-66　2003
Advanced Fluid Information Research in Institute of Fluid Science

Kentaro MORI, Takashi TOKUMASU, Toshiaki IKOHAGI

AFI-2003　73-74　2003
不純物混入液体における気泡核生成の分子動力学的研究

津田伸一, 徳増崇, 高木周, 松本洋一郎

日本機械学会2003年度年次大会講演論文集(VI)　2003　183-184　2003
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2003.6.0_183 　

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In the present study, molecular dynamics simulation is applied to the analysis of the bubble nucleation in liquid oxygen including helium or nitrogen as impurities. All molecular interactions are given by the Lennard-Jones potential and simulations are excuted under the standard boiling point of oxygen (90K). Under a high concentration, helium molecules make a cluster based on the phase separation while nitrogen molecules do not. In addition, it is found that the effect of helium molecules which make a bigger local void under a lower concentration is strong while the nitrogen molecules make a smaller one even under a higher concentration. Based on the simulation results, it is pointed out that the helium molecules have a possibility to raise the nucleation point even under a lower concentration while nitrogen ones do not so much.
Investigation of Thermal Conductivity of Diatomic Liquid by Molecular Dynamics Method Peer-reviewed

Takashi Tokumasu, Taku Ohara, Kenjiro Kamijo

Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B　69　(683)　1644-1650　2003
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.69.1644 　

ISSN： 0387-5016
An improved method for the estimation of rotational temperature with a weak electron beam Peer-reviewed

Takashi Tokumasu, Yoichiro Matsumoto

Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B　68　(676)　3352-3359　2002
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.68.3352 　

ISSN： 0387-5016
A numerical study of thermodynamic effects of sheet cavitation Peer-reviewed

Takashi Tokumasu, Kenjiro Kamijo, Yoichiro Matsumoto

American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED　257　(1 A)　377-382　2002

DOI： 10.1115/FEDSM2002-31008 　
Molecular dynamics study of heterogeneous bubble nucleation in liquid oxygen including helium, nitrogen, or argon Peer-reviewed

Shin-Ichi Tsuda, Takashi Tokumasu, Kenjiro Kamijo, Yoichiro Matsumoto

American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED　257　(1 A)　455-460　2002

DOI： 10.1115/FEDSM2002-31022 　
二原子分子流体の熱物性に回転自由度が及ぼす影響

徳増崇, 上條謙二郎, 小原拓, 松本洋一郎

日本機械学会2002年度年次大会講演論文集(IV)　2002　33-34　2002
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2002.4.0_33 　

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In this paper the effect of rotational degree of freedom on the properties of liquid is analyzed by the Molecular Dynamics (MD) Method. Oxygen is assumed as the liquid and molecules are assumed as both monatomic and diatomic one. 2 center Lennard-Jones (2CLJ) potential is assumed as the intermolecular potential for diatomic molecules and Lennard-Jones (LJ) potential is used for monatomic molecule. Simulations are performed at various combinations of density and temperature and an Equation of State (EOS) of each liquid is obtained by using these results. The parameters of each potential are determined so that the critical temperature and density are consistent with each other. The properties of liquid such as, latent heat, specific heat, thermal conductivity and surface tension are compared with each other and the effect of rotational degree of freedom on the properties of liquid is investigated.
液体中における不純物の挙動の分子動力学的解析

津田伸一, 徳増崇, 上條謙二郎, 松本洋一郎

日本機械学会2002年度年次大会講演論文集(IV)　2002　35-36　2002
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2002.4.0_35 　

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Heterogeneous bubble nucleation in liquid oxygen including helium or nitrogen is simulated by usint the molecular dynamics method. Molecular interaction is given as Lennard-Jones potential, and each potential parameter is determined so that it well expresses the thermodynamic properties of factual fluids. In the case that helium is the impurity, clustering of helium molecules is observed through the simulation and these clusters are considered to become bubble nuclei. On the other hand, nitrogen molecules do not make a cluster in liquid oxygen under the same condition, and bubble is formed based on the density fluctuation as same as unary liquid oxygen. Therefore, helium in the liquid oxygen has a fairly stronger action to make clusters as bubble nuclei.
ロケットエンジン推進剤供給系の動的挙動の解析

全相仁, 徳増崇, 上條謙二郎

日本機械学会2002年度年次大会講演論文集(III)　2002　183-184　2002
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2002.3.0_183 　

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Many rocket launch failures are caused by engine problem, especially by the propellant feed system problem. Analysis of transient or unsteady characteristics of turbopump system is necessary on conducting rocket engine stability analysis such as POGO analysis. Dynamic characteristics of cavitating inducer isn't governed only by cavitation compliance defined as the ratio of cavity volume change rate to inducer inlet pressure change rate, but also by mass flow gain factor defined as the ratio of cavity volume change rate to inducer inlet mass flow change rate. This paper provides a new dynamic model of rocket engine LH_2 feed system and gives some stability analysis results.
Molecular dynamics study for thermodynamic properties of diatomic fluid (the effect of rotational degree of freedom on properties of fluid) Peer-reviewed

Takashi Tokumasu, Kenjiro Kamijo, Taku Ohara, Yoichiro Matsumoto

Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B　68　(668)　1227-1234　2002
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.68.1227 　

ISSN： 0387-5016
Multi-Scale Analysis of Non-Equilibrium Hypersonic Rarefied Gas Flow

Matsumoto,Y, Tsuboi,N, Tokumasu,T, Yamanishi,N

Computational Fluid Dynamics Journal　9　(1-Ⅰ)　459-470　2001
Multi-scale analysis of non-equilibrium hypersonic rarefied gas flows Peer-reviewed

Yoichiro Matsumoto, Nobuyuki Tsuboi, Takashi Tokumasu, Nobuhiro Yamanishi

Computational Fluid Dynamics Journal, Special Number　23-34　2001
大きな外乱を受けたロケットポンプの非定常特性 Peer-reviewed

Takashi Tokumasu, Sangin Jun, Kenjiro Kamiro, Masahiro Atsumi

ターボ機械　29　(3)　155-160　2001
Publisher: Turbomachinery Society of Japan
DOI： 10.11458/tsj1973.29.155 　

ISSN： 0385-8839
Molecular Dynamics study of the nucleation of bubble Peer-reviewed

Takashi Tokumasu, Kenjiro Kamijo, Mamoru Oike, Yoichiro Matsumoto

CAV2001　A1-005　2001
Observation of helium two-phase flows in a pipe Peer-reviewed

Mamoru Oike, Takashi Tokumasu, Kenjiro Kamijo

CAV2001　A8-002　2001
The thermodynamic effects of cavitation around a 2-D hydrofoil

Takashi Tokumasu, Kenjiro Kamijo, Yumiko Sekino, Yoichiro Matsumoto

AFI-2001　297-302　2001
Observation of two-phase cryogenic flows in a horizontal pipe

Mamoru Oike, Takashi Tokumasu, Kenjiro Kamijo

AFI-2001　281-286　2001
Dynamic Molecular Collision model for N-2-He mixture Peer-reviewed

T Tokumasu, Y Matsumoto, K Kamijo, M Oike

RAREFIED GAS DYNAMICS　585　645-652　2001

ISSN： 0094-243X
キャビテーションに対する熱力学的効果の数値解析

関野夕美子, 徳増崇, 上條謙二郎

第41回航空原動機・宇宙推進講演会講演集　285-290　2001
極低温ロケットポンプインデューサのキャビテーションに対する熱力学的効果

関野夕美子, 徳増崇, 上條謙二郎

日本航空宇宙学会北部支部2001年講演会および第2回再使用型宇宙推進系シンポジウム講演論文集　169-174　2001
気泡生成における分子内自由度の影響

徳増崇, 上條謙二郎, 松本洋一郎

日本機械学会流体工学部門講演会講演概要集　201　2001
不純物粒子を含む液体酸素中における不均一気泡核生成の分子動力学的解析

津田伸一, 徳増崇, 上條謙二郎, 松本洋一郎

日本機械学会流体工学部門講演会講演概要集　810　2001
極低温管内気液二相流特性の観察

大西将弘, 尾池守, 徳増崇, 上條謙二郎

日本機械学会流体工学部門講演会講演概要集　811　2001
極低温流体中でのシートキャビティの数値解析

徳増崇, 上條謙二郎, 関野夕美子, 松本洋一郎

キャビテーションに関するシンポジウム(第11回)講演論文集　125-128　2001
極低温管内気液二相流動特性の観察

大西将弘, 尾池守, 徳増崇, 上條謙二郎

流体力学シンポジウム '01 講演論文集　9-12　2001
不純物粒子を含む液体酸素中における不均一気泡核生成の分子動力学的解析

津田伸一, 徳増崇, 上條謙二郎, 松本洋一郎

流体力学シンポジウム '01 講演論文集　13-16　2001
Construction of collision model of diatomic molecules (Improvement of energy transfer model and its verification) Peer-reviewed

T Tokumasu, Y Matsumoto

JSME INTERNATIONAL JOURNAL SERIES B-FLUIDS AND THERMAL ENGINEERING　43　(2)　288-295　2000/05

DOI： 10.1299/jsmeb.43.288 　

ISSN： 1340-8054
Bubble Nucleation in Liquid Oxygen Peer-reviewed

Takashi Tokumasu, Kenjiro Kamijo, Mamoru Oike, Yoichiro Matsumoto

ASME FEDSM 2000　FEDSM2000-11019　2000
"Dynamic Molecular Collision (DMC) Model of Diatomic Molecules Peer-reviewed

Takashi Tokumasu, Yoichiro Matsumoto

Proc. 21th Rarefied Gas Dynamics　2　377-384　1999/07
Dynamic molecular collision (DMC) model for rarefied gas flow simulations by the DSMC method Peer-reviewed

T Tokumasu, Y Matsumoto

PHYSICS OF FLUIDS　11　(7)　1907-1920　1999/07

DOI： 10.1063/1.870053 　

ISSN： 1070-6631
The Structure of Free Jet Expansion of Binary Gas Mixture Peer-reviewed

Takashi Tokumasu, Yoichiro Matsumoto, Kenjiro Kamijo, Mamoru Oike

Thermal Science and Engineering　7　17-22　1999
液体酸素中における気泡生成機構の分子動力学的解析

徳増崇, 松本洋一郎, 上條謙二郎, 尾池守

日本流体力学会年会 '99 講演論文集　17-18　1999
液体酸素中における気泡生成機構の分子動力学的解析

徳増崇, 松本洋一郎, 上條謙二郎, 尾池守

液体酸素中における気泡生成機構の分子動力学的解析　1999　18-23　1999
Publisher:
ISSN： 1344-2236
The Construction of Collision Model of Diatomic Molecules

Takashi Tokumasu, Yoichiro Matsumoto

Colloquium on Nonequilibrium Phenomena of Low-Density Jets in Space　93-100　1998/02
Construction of Collision Model of Diatomic Molecules (4th Report, Improvement of Energy Transfer Model and Its Verification) Peer-reviewed

TOKUMASU Takashi

Transactions of the Japan Society of Mechanical Engineers B Series　64　(627)　3551-3557　1998
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.64.3551 　

ISSN： 0387-5016

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In the 3rd report, we introduced an LJ potential parameter which is based on the potential obtained from ab-initio calculation and collision cross section from the Wang-Chang Uhlenbeck and Taxmas's theory and Molecular Dynamics (MD) calculation. In this 4th paper, we improved a Dynamic Molecular Collision (DMC) model to calculate the property of MD simulation better than the former one. To make sure of its validity we calculated equilibrium state, transport coefficient (viscosity coefficient, heat conductivity) at some temperatures and normal shock wave by the DSMC method using DMC model and compared these results with other theoretical and experimental results. Consequently, we found that the diatomic rarefied gas flows could be simulated very well using our model.
Construction of Collision Model of Diatomic Molecules (3rd Report, Improvement of Collision Model) Peer-reviewed

TOKUMASU Takashi

Transactions of the Japan Society of Mechanical Engineers B Series　64　(627)　3544-3550　1998

DOI： 10.1299/kikaib.64.3544 　
Non-Equilibrium Hypersonic Diatomic Molecular Flow Simulation Peer-reviewed

Matsumoto, Y, Tsuboi, N, Tokumasu, T, Yamanishi, N

Modeling and Simulation Based Engineering　1　893-898　1998
超音速自由噴流場中の回転温度分布

徳増崇, 松本洋一郎

第75期通常総会講演会講演論文集　98　253-254　1998
分子の衝突力学に基づく二原子分子衝突モデル

徳増崇, 松本洋一郎

第12回数値流体力学シンポジウム講演論文集　103-104　1998
Parallel computing of diatomic molecular rarefied gas flows Peer-reviewed

Y Matsumoto, T Tokumasu

PARALLEL COMPUTING　23　(9)　1249-1260　1997/09

DOI： 10.1016/S0167-8191(97)00051-3 　

ISSN： 0167-8191
Interaction Potential of Diatomic Molecule for Molecular Dynamics Calculation Peer-reviewed

Takashi Tokumasu, Yoichiro Matsumoto

Proc. 20th Rarefied Gas Dynamics　737-742　1997/07
The Numerical Simulations of Diatomic Rarefied Gas Flows

Takashi Tokumasu, Yoichiro Matsumoto

Proc. International Conference on Fluid Engineering　3　1235-1240　1997/07
二原子分子流れにおける超音速自由噴流場の流動構造

徳増崇, 松本洋一郎

徳増崇, 松本洋一郎　94-95　1997
二原子分子非平衡流の数値シミュレーション

徳増崇, 松本洋一郎

日本流体力学会年会 '97 講演論文集　16　17-18　1997

ISSN： 1342-8004
二原子分子自由噴流場の流動構造

徳増崇, 松本洋一郎

第11回数値流体力学シンポジウム講演論文集　101-102　1997
Construction of Collision Model of Diatomic Molecules (1st Report, the MD Simulation of Molecular Collision) Peer-reviewed

TOKUMASU Takashi

Transactions of the Japan Society of Mechanical Engineers B Series　62　(595)　864-871　1996
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.62.864 　

ISSN： 0387-5016

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At present, the DSMC method is the best scheme to analyze rarefied gas flows. However, polyatomic inelastic collisions which have complicated energy transfer between translational and internal degree of freedom cannot be analyzed accurately. In this paper, a model for energy exchange between translational and rotational degrees of freedom is constructed using the results of MD simulation. In this 1st report, we describe how to simulate the collision of diatomic molecules by the MD method and the results of the simulation, We find that the energy transfer is distributed without a characteristic relation to the direction and orientation of the rotational vector, and that both the energy transfer and collisional cross section strongly depend on the initial translational and rotational energy.
Construction of Collision Model of Diatomic Molecules (2nd Report, Construction of the Model and Its Verification) Peer-reviewed

TOKUMASU Takashi

Transactions of the Japan Society of Mechanical Engineers B Series　62　(595)　872-879　1996
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaib.62.872 　

ISSN： 0387-5016

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In the 1st report, we made some calculations to obtain data in order to construct a model for collision of diatomic molecules. Consequently, we found that the energy transfer is distributed without a characteristic relation to the direction and orientation of the rotational vector, and that both the energy transfer and collisional cross section strongly depend on the initial translational and rotational energy In this 2nd paper, we constructed a collision model for diatomic molecules using these data. To make sure of its validity we calculated equilibrium state, viscosity coefficient, heat conductivity diffusion coefficient and normal shock wave by the DSMC method using our model and compared these results with other theoretical and experimental results. Consequently, we found that the diatomic rarefied gas flows can be simulated very well using our model.
二原子分子気体中の衝撃波の構造

前田英志, 徳増崇, 松本洋一郎

平成5年度衝撃波シンポジウム講演論文集　83-86　1996
二原子分子衝突モデルの構築と希薄気体流れ解析への応用

前田英志, 徳増崇, 松本洋一郎

第73期通常総会講演会講演論文集　169-170　1996
二原子分子気体流れの数値シミュレーション

徳増崇, 松本洋一郎

日本流体力学会年会 '96 講演論文集　15　225-226　1996

ISSN： 1342-8004
二原子分子衝突の量子分子動力学シミュレーション

徳増崇, 松本洋一郎

第74期全国大会講演論文集　327-328　1996
二原子分子衝突モデルと輸送物性計算

徳増崇, 松本洋一郎

第10回数値流体力学シンポジウム講演論文集　286-287　1996
Collision Model of Diatomic Molecules for DSMC Method Peer-reviewed

Yoichiro Matsumoto, Takashi Tokumasu

Proc. 19th Rarefied Gas Dynamics　2　808-814　1995/07
二原子分子衝突の動力学

徳増崇, 松本洋一郎

第73期全国大会講演論文集　71-72　1995
二原子分子衝突モデルの構築

前田英志, 徳増崇, 松本洋一郎

第73期全国大会講演論文集　73-74　1995
分子動力学法における二原子分子ポテンシャルの影響

分子動力学法における二原子分子ポテンシャルの影響

第8回計算力学講演会講演論文集　373-374　1995
Cluster Formation of Diatomic Molecules Peer-reviewed

Yoichiro Matsumoto, Takashi Tokumasu

Thermal Science and Engineering　2　(1)　138-144　1994

ISSN： 0918-9963
DSMC法における二原子分子衝撃波の構造解析

徳増崇, 松本洋一郎

平成5年度衝撃波シンポジウム講演論文集　187-190　1994
二原子分子の衝突 -その動力学とモデルの構築

徳増崇, 前田英志, 松本洋一郎

第8回数値流体力学シンポジウム講演論文集　133-136　1994
The Construction of Collision Model of Diatomic Molecules in DSMC Method

Takashi Tokumasu, Yoichiro Matsumoto

Proc. the International Symposium on Aerospace and Fluid Science　610-617　1993/11
二原子分子衝突過程の可視化

徳増崇, 松本洋一郎

第21回可視化情報シンポジウム講演論文集　13　(1)　99-102　1993
Publisher: The Visualization Society of Japan
DOI： 10.3154/jvs.13.Supplement1_99 　

ISSN： 0916-4731

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The collison of N2 molecules in which only rotation of molecules is regarded as internal degree of freedom is simulated and the energy transfer between translational and rotational energy is investigated numerically at low temperature. The results are visualized and it is shown that energy transfer changes by the direction and orientation of rotational vector and the impact parameter and it is also distributed in some form according to the initial translational and rotational energy. Using these results, the collision model of diatomic molecule is constructed and is applied to the Direct Simulation Monte Carlo Method and some properties of fluids, for instance, the energy distribution at equiliblium condition and so on, are calculated for making sure of its validity. It is shown that the collision process of diatomic molecules can be calculated well by use of this model.
二原子分子の非弾性衝突モデル

徳増崇, 松本洋一郎

第71期全国大会講演論文集　426-428　1993
マクロ液膜の構成機構に関する研究

庄司正弘, 黒木博史, 徳増崇

第29回日本伝熱シンポジウム講演論文集　432-433　1992
二原子分子衝突モデルの構築

徳増崇, 松本洋一郎

第5回計算力学講演会講演論文集　253-254　1992
DSMC法における二原子分子衝突モデル

徳増崇, 松本洋一郎

第6回数値流体力学シンポジウム講演論文集　167-170　1992

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Misc. 90

A molecular dynamics study of the ionomer film formation during drying process in fuel cell catalyst layer

GUO Yuting, 馬渕拓哉, LI Gaoyang, 徳増崇

日本伝熱シンポジウム講演論文集(CD-ROM)　60th　2023

ISSN： 1346-1532
A Molecular Dynamics Study of the Effect of Pt/C Substrate on Adsorption and Morphological Changes of Ionomers in the Catalyst Layer

GUO Yuting, 馬渕拓哉, LI Gaoyang, 徳増崇

日本伝熱シンポジウム講演論文集(CD-ROM)　59th　2022

ISSN： 1346-1532
固体高分子形燃料電池触媒層作成における塗布・乾燥工程の分子シミュレーション

徳増崇, 馬渕拓哉, 郭玉てい

化学工学会秋季大会研究発表講演要旨集(CD-ROM)　52nd　2021
Oxygen Transport Analysis Considering Surface Diffusion of Ionomer in Catalyst Layer of Polymer Electrolyte Fuel Cell

堀智紀, 馬渕拓哉, 杵淵郁也, 徳増崇

燃料電池シンポジウム講演予稿集(CD-ROM)　28th　2021
Evaluation of the transport and structure characteristics of polymer electrolyte fuel cell by molecular simulations

徳増崇, 馬渕拓哉

燃料電池シンポジウム講演予稿集(CD-ROM)　28th　2021
Analysis of Oxygen Transport Resistance in Catalyst Layer of Polymer Electrolyte Fuel Cell Based on Molecular Scattering Phenomena

中内将隆, 馬渕拓哉, 吉本勇太, 金子敏宏, 杵淵郁也, 武内秀樹, 徳増崇

東北大学流体科学研究所共同利用・共同研究拠点流体科学国際研究教育拠点活動報告書　2019 (CD-ROM)　2021
Coarse-grained Molecular Dynamics Study of Ionomer Dispersions in Water/Alcohol Solutions

馬渕拓哉, 徳増崇

日本伝熱シンポジウム講演論文集(CD-ROM)　57th　2020

ISSN： 1346-1532
Molecular dynamics study of cerium ion transport properties in polymer electrolyte membrane

石川恭平, 馬渕拓哉, 徳増崇

日本伝熱シンポジウム講演論文集(CD-ROM)　57th　2020

ISSN： 1346-1532
Molecular Dynamics Study of Surface Reaction Mechanisms in Chemical Vapor Deposition Processes.

上根直也, 馬渕拓哉, 財津優, 安原重雄, 徳増崇

日本伝熱シンポジウム講演論文集(CD-ROM)　57th　2020

ISSN： 1346-1532
Analysis of CVD/ALD thin film deposition mechanism by reactive molecular dynamics simulation and quantum chemical calculation

徳増崇, 上根直也, 上根直也, 馬渕拓哉, 馬渕拓哉, 財津優, 安原重雄

電子情報通信学会技術研究報告(Web)　120　(239(SDM2020 22-34))　2020

ISSN： 2432-6380
Molecular Dynamics Study of carbon diffusion inside iron under an electric field

北快理, 馬渕拓哉, CHANTRENNE Patrice, 徳増崇

数値流体力学シンポジウム講演論文集(CD-ROM)　34th　2020

ISSN： 2433-2674
Molecular Dynamics Study of Proton Transport in Nafion / Carbon Nanotubes Composite Membranes

田中陸機, 馬渕拓哉, ZANG Yushi, HINDS Bruce, 徳増崇

数値流体力学シンポジウム講演論文集(CD-ROM)　34th　2020

ISSN： 2433-2674
Molecular analysis of cerium ion transport in hydrated Nafion membrane

石川恭平, 石川恭平, 馬渕拓哉, 馬渕拓哉, 徳増崇

日本機械学会マイクロ・ナノ工学シンポジウム講演論文集(CD-ROM)　11th　2020

ISSN： 2432-9495
Analysis of Transport and Structure Characteristics of Polymer Electrolyte Fuel Cell by Molecular Simulations

徳増崇, 馬渕拓哉

燃料電池シンポジウム講演予稿集　27th　2020
Analysis of Oxygen Transport Resistance in Catalyst Layer of Polymer Electrolyte Fuel Cell Based on Molecular Scattering Phenomena

中内将隆, 馬渕拓哉, 吉本勇太, 金子敏宏, 杵淵郁也, 武内秀樹, 徳増崇

東北大学流体科学研究所共同利用・共同研究拠点流体科学国際研究教育拠点活動報告書　2018　2020
Molecular Analysis of Ionomer Aggregate Structures During Evaporation Process of Water/Alcohol Solutions

馬渕拓哉, 馬渕拓哉, 徳増崇

日本機械学会年次大会講演論文集(CD-ROM)　2019　2019

ISSN： 2424-2667
触媒層微小流路における酸素輸送現象の分子論的解析

中内将隆, 馬渕拓哉, 吉本勇太, 金子敏宏, 杵淵郁也, 武内秀樹, 徳増崇

日本伝熱シンポジウム講演論文集(CD-ROM)　56th　2019

ISSN： 1346-1532
PEFC触媒層における酸素拡散機構の分子論的解析

中内将隆, 馬渕拓哉, 吉本勇太, 金子敏弘, 杵淵郁也, 武内秀樹, 徳増崇

数値流体力学シンポジウム講演論文集(CD-ROM)　32nd　2018

ISSN： 2433-2674
アイオノマー表面における酸素分子表面拡散現象の分子論的解析

中内将隆, 馬渕拓哉, 吉本勇太, 金子敏宏, 杵淵郁也, 武内秀樹, 徳増崇

日本機械学会年次大会講演論文集(CD-ROM)　2018　2018

ISSN： 2424-2667
Large Scale Molecular Simulations for the Structure and Transport Characteristics of Polymer Electrolyte Fuel Cell

17　(1)　53-62,巻頭1p　2017
Publisher: 燃料電池開発情報センター
ISSN： 1346-6623
C225 Molecular Dynamics Study of Friction Force around the Contact Line

Fukushima Akinori, Tokumasu Takashi

Procee[d]ings of Thermal Engineering Conference　2015　"C225-1"-"C225-2"　2015/10/23
Publisher: The Japan Society of Mechanical Engineers

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In this study, we have evaluated the force around the contact line by Molecular Dynamics Simulation. Using nine different-sized nano channel, we evaluated the channel size dependence of the friction force around the contact line region by one component of the stress tensor. Compared with the force evaluated by dynamic contact angles, we can say that in the case that the channel size is smaller than 10 nm, the friction forces evaluated by the shear stress do not agree with the force by the dynamic contact angles.
J0560104 Analysis of Proton Transport Phenomena in Polymer Electrolyte Membrane Using Molecular Dynamics Simulations

MABUCHI Takuya, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2015　"J0560104-1"-"J0560104-3"　2015/09/13
Publisher: The Japan Society of Mechanical Engineers

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The effects of water cluster structures on the PT properties have been investigated using reactive molecular dynamics (MD) simulations. The two-state empirical valence bond (aTS-EVB) model was used to allow proton transport (PT) phenomena including the Grotthuss mechanism to be simulated within the simplicity of the theoretical framework in MD simulations. The systems were constructed to reproduce the experimentally proposed hydrophilic cluster structures (the cylinder model, the lamellar model, and the sphere-rod model) in the Nafion systems. The diffusion coefficients in each dimension were estimated to characterize PT properties. It was found that proton diffusion strongly correlates with the cluster size as well as the type of cluster models. The proton diffusion in the lamellar model is higher than that in the other two types of models when the water volumes are the same. In addition, the rod radius in the sphere-rod model, i.e., the bottleneck of the cluster domain, strongly affects the proton diffusion, suggesting that the rod radius, regardless of the sphere radius, is a dominant factor for the proton diffusion in the sphere-rod model.
J0540302 A discussion on the effect of quantum nature on bubble inception in liquid hydrogen using molecular simulation

KATAYAMA Chiharu, NAGASHIMA Hiroki, TOKUMASU Takashi, WATANABE Satoshi, TSUDA Shin-ichi

Mechanical Engineering Congress, Japan　2015　"J0540302-1"-"J0540302-5"　2015/09/13
Publisher: The Japan Society of Mechanical Engineers

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Recently, application of hydrogen energy has been expanded. For more safe and efficient use of hydrogen, study of bubble nucleation in liquid hydrogen is necessary. Various studies already have reported the quantum nature effects on thermodynamic and transport properties. Therefore, it is expected that quantum nature also influences bubble nucleation. We reproduced quantum liquid hydrogen using path integral centroid Molecular Dynamics (MD) method and also simulated virtual classical liquid hydrogen with classical MD. First, we compared the energy barrier for bubble nucleation and the critical bubble size using Classical Nucleation Theory. Next, we investigated quantity of void in both fluids with local density function. In consequence, it is suggested that quantum nature affects bubble nucleation, and quantum hydrogen is difficult to create a bubble nucleus than classical hydrogen.
J0560106 Oxygen Permeability in Cathodic Ionomer Using Different Types of Polymer Electrolyte Membranes

KURIHARA Yuya, MABUCHI Takuya, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2015　"J0560106-1"-"J0560106-4"　2015/09/13
Publisher: The Japan Society of Mechanical Engineers

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Using two different types of ionomers which are composed of perfluorosulfonic acid (PFSA) and hydrocarbon (HC), we constructed systems of the ionomers on Pt catalyst surface, and investigated water content dependence on oxygen permeability in the ionomers using molecular dynamics simulations. We have found that the oxygen permeability of the PFSA ionomer is better than that of the HC ionomer. Moreover, the oxygen permeability decreases as water content increases in the both ionomers. Next, we analyzed density distributions of the ionomer components and oxygen solubility in the ionomers. As a result, in the PFSA ionomer, the oxygen permeability decreases because the oxygen solubility decreases due to the increase in the solvent molecules. On the other hand, in the HC ionomer, the solvent molecules accumulate on the surface of high-density polymers and block the oxygen permeation.
J0540202 A Study on Flow Property of Nanoscale Gas Flow in Porous Media

KAWAGOE Yoshiaki, YONEMURA Shigeru, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2015　"J0540202-1"-"J0540202-4"　2015/09/13
Publisher: The Japan Society of Mechanical Engineers

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Gas flow in porous media is used in industrial processes such as dissociation reaction, desiccation, adsorption and reduction reaction. It is important to understand flow phenomena in porous media for improving of performance of devices including such processes. However, gas flow in nanoscale porous media is cannot treated as a continuum and the flow property is not yet clear. In this study, we analyzed the nanoscale gas flow in the porous media by using the DSMC simulations and proposed the model predicting the velocity of gas flow.
J0560105 Molecular Dynamics Simulations of Proton Transport in Cathode Catalyst Layer of PEFC

AOCHI Joji, MABUCHI Takuya, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2015　"J0560105-1"-"J0560105-4"　2015/09/13
Publisher: The Japan Society of Mechanical Engineers

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We have investigated proton transport property in polymer thin films in cathode catalyst layer (CL) of polymer electrolyte fuel cell using molecular dynamics simulations to characterize nanoscopic flow phenomena observed in CL. In the CL, polymer thin films cover supported carbon, and it is well known that the wettability of supported carbon depends on operating environments and materials. Therefore we have focused on the effect of the wettability of supported carbon on the structure of polymer thin films and proton transport. In this study, three different wettability surfaces, which are hydrophobic, intermediate, and hydrophilic, respectively, were used. It was found that the structure of polymer thin films strongly depends on the wettability of surface. Especially, the distribution of water molecules is different depending on the characteristic of each surface, leading to distinctive proton transport property because water clusters are served as a proton conductive path. A correlation between the structure of polymer thin films and the proton transport was also discussed.
機械工学年鑑，7. 流体工学

西山秀哉, 福西祐, 伊澤精一郎, 浅井圭介, 澤田恵介, 孫明宇, 祖山均, 石本淳, 山本悟, 伊賀由佳, 須藤誠一, 中野政身, 佐藤岳彦, 高奈秀匡, 徳増崇, 米村茂, 早瀬敏幸, 石川拓司

日本機械学会誌　118　(1161)　27-33　2015/08/05
Publisher: 日本機械学会
大規模分子シミュレーションによる固体高分子形燃料電池(PEFC)内物質輸送現象の解明(トピックス)

徳増崇

日本機械学會誌　118　(1155)　90-90　2015/02/05
Publisher: 一般社団法人日本機械学会
ISSN： 0021-4728
J0540307 Molecular Dynamics Analysis of static and dynamic fluctuation structure of diatomic fluids around the critical point

Ikawa Shohei, Nagashima Hiroki, Tsuboi Nobuyuki, Tokumasu Takashi, Tsuda Shin-ichi

Mechanical Engineering Congress, Japan　2015　"J0540307-1"-"J0540307-5"　2015
Molecular Simulation of Oxygen Permeability through Ionomer in PEFC

Kurihara Yuya, Mabuchi Takuya, Tokumasu Takashi

The Computational Mechanics Conference　2014　(27)　703-704　2014/11/22
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-026X

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Using two different types of ionomers which are comprised of Nafion and hydrocarbon, we constructed systems of the ionomers on Pt catalyst surface, and investigated water content dependence on oxygen permeability in the ionomers using molecular dynamics simulations. We have found that the oxygen permeability of the Nafion-based ionomer is better than that of the hydrocarbon-based ionomer. Furthermore, the number of permeated oxygen molecules decreases with increasing water content on the both ionomers. Moreover, we analyzed density distributions of the ionomer components and solubility distributions of oxygen in the ionomers. As the results, in the ionomer-gas interface and bulk region of the both ionomers, the solvent molecules which increase as water content increases, block the oxygen permeation. In the ionomer-Pt interface of Nafion-based ionomer, the solvent occupies the pathways for oxygen permeation, while in the interface of hydrocarbon-based ionomer, the solvent which are piled up on the surface of high-density polymers, blocks the oxygen permeation.
Molecular dynamics study of the channel size dependence of the friction force between nanoscale droplets and solid walls

Fukushima Akinori, Mima Toshiki, Kinefuchi Ikuya, Tokumasu Takashi

The Computational Mechanics Conference　2014　(27)　705-706　2014/11/22
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-026X

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We report the channel size dependence of the forces that act on water droplets in a nano-meter order channel. Considering the several different-sized channel models, we evaluate forces between the two hydrophobic walls and water droplets by molecular dynamics simulation and show the channel size dependence in terms of the mechanical coefficients, such as friction coefficient. As a result, we show that the friction coefficient depends on the channel size due to the normal pressure. From these results, we clarify that there is the different channel size dependence of the static and dynamic properties of the water droplet compared with the macroscopic case.
B213 A Study of the Density Fluctuation of Diatomic Fluids around the Critical Point by Molecular Dynamics Simulation

Ikawa Shohei, Tokumasu Takashi, Nobuyuki Tsuboi, Nagashima Hiroki, Tsuda Sin-ichi

Procee[d]ings of Thermal Engineering Conference　2014　"B213-1"-"B213-2"　2014/11/08
Publisher: The Japan Society of Mechanical Engineers

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In this study, we evaluated the density fluctuation of diatomic fluids around the critical point. We performed Molecular Dynamics (MD) simulation against 2-Center-Lenard-Jones (2CLJ) fluids that have molecular elongation as a parameter. We compared the density fluctuation of each fluid to evaluate the principle of corresponding state of density fluctuation. We evaluated the density fluctuation by dispersion of number of molecules, static structure factor, and intermediate scattering function. As the results, in 2CLJ fluids that have shorter molecular elongation comparatively, the principle of corresponding state of static fluctuation structure was satisfied.
B212 Molecular dynamics simulation of wettability and pore diameter dependence of saturation pressure of water in nanocylinders

Mima Toshiki, Kinefuchi Ikuya, Yoshimoto Yuta, Fukushima Akinori, Tokumasu Takashi, Takagi Shu, Matsumoto Yoichiro

Procee[d]ings of Thermal Engineering Conference　2014　"B212-1"-"B212-2"　2014/11/08
Publisher: The Japan Society of Mechanical Engineers

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Molecular dynamics simulations (MD) are carried out in order to investigate the wettability and pore size dependence of the saturation pressure of the water molecules in nanocylinder and to verify the Kelvin equation. The Kelvin equation quantitatively coincides to the MD results for the nanocylinders with the diameter of 4.2 and 5.2 nm in the case of the intermediate-wetting and hydrophilic nanocylinders. In the case of the hydrophobic nanocylinder, the saturation pressures are at most 10% higher than the estimation of the Kelvin equation with the diameter from 2.2 nm to 5.2 nm.
J0550104 Evaluation of the Density Fluctuation against the Diatomic Fluids around the Critical Points using Molecular Dynamics Simulation

IKAWA Shohei, TOKUMASU Takashi, TSUBOI Nobuyuki, TSUDA Shin-ichi

Mechanical Engineering Congress, Japan　2014　"J0550104-1"-"J0550104-4"　2014/09/07
Publisher: The Japan Society of Mechanical Engineers

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In this study, we investigated the density fluctuation of diatomic fluids around the critical points for evaluation of the principle of corresponding state. We used Molecular Dynamics (MD) simulation against the 2-Center Lennard-Jones (2CLJ) fluids for extraction of structure of fluctuation around the critical points. We evaluated the density fluctuation by two methods. One is the dispersion of number of molecules at certain domain as time-averaged quantity. The other is the calculation of static structure factor. As the results, in 2CLJ fluids that have shorter molecular elongations comparatively, the principle of corresponding state is satisfied because of the small difference in the fluctuation structure extracted by the present two methods.
J0610101 Numerical Analysis of Proton Conductivity in Polymer Electrolyte Membrane Contaminated with metal ion

KAWAI Kiyoto, MABUCHI Takuya, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2014　"J0610101-1"-"J0610101-4"　2014/09/07
Publisher: The Japan Society of Mechanical Engineers

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We performed a numerical analysis of the influences of contaminated metal ion on the dynamic properties of proton in a polymer electrolyte membrane (PEM). It was revealed that the nanostructure of the PEM was changed greatly with increasing the concentration of ferric ions. The diffusion coefficient of hydronium ions increases larger at higher water contents with increasing the concentration of ferric ions because of the lower concentration of cations. At higher water contents, the hydronium diffusion coefficient increases largely because ferric ions reduce the electrostatic interactions between hydronium ions and sulfonate groups. At lower water contents, by contrast, the structures between ferric ions and sulfonate groups hinder the hydronium motions resulting in a small increase in the hydronium diffusion coefficient.
J0550105 Channel size dependence of the friction force between water droplets and solid walls

FUKUSHIMA Akinori, MIMA Toshiki, KINEFUCHI Ikuya, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2014　"J0550105-1"-"J0550105-5"　2014/09/07
Publisher: The Japan Society of Mechanical Engineers

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We report the channel size dependence of the forces that act on water droplets in a nano-meter order channel. Considering the several different-sized channel models, we evaluate forces between the two hydrophobic walls and water droplets by molecular dynamics simulation and show the channel size dependence in terms of the mechanical coefficients, such as friction coefficient. As a result, we show that when the channel size is less than 50Å, the pressure inside water droplet is larger than the expected values from Young-Laplace equation. Moreover we also clarify that this disagreement derives from the difference between a channel size and a droplet size. In the case of the friction force, we show that the friction coefficient depends on the channel size due to the Laplace pressure. From these results, we clarify that there is the different channel size dependence of the static and dynamic properties of the water droplet compared with the macroscopic case.
J0550204 An Analysis of Quantum Effect on the Transport Properties of Liquid Hydrogen using Molecular Dynamics Method

NAGASHIMA Hiroki, TSUDA Shinichi, TSUBOI Nobuyuki, KOSHI Mitsuo, HAYASHI Koichi, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2014　"J0550204-1"-"J0550204-4"　2014/09/07
Publisher: The Japan Society of Mechanical Engineers

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In this study, we conducted analysis of quantum effect of hydrogen molecules on the energy transport of liquid hydrogen using classical Molecular Dynamics (MD) and path integral Centroid MD (CMD) method. We performed MD simulation across a wide temperature region in the constant density and compared the thermal conductivity of each method. The thermal conductivity was calculated using non-equilibrium MD method. As a result, it was confirmed that CMD shows lower thermal conductivity than classical MD and this tendency is consistent with experimental data. Moreover, it was clarified that because of the change of intermolecular potential due to the quantum effect, the potential energy transport by molecular motion and the energy transport by intermolecular interaction decrease.
J0550203 Molecular Dynamics Simulation of Pore Diameter Dependence of Saturation Pressure of Water in Nanocylinder

MIMA Toshiki, KINEFUCHI Ikuya, YOSHIMOTO Yuta, FUKUSHIMA Akinori, TOKUMASU Takashi, TAKAGI Shu, MATSUMOTO Yoichiro

Mechanical Engineering Congress, Japan　2014　"J0550203-1"-"J0550203-4"　2014/09/07
Publisher: The Japan Society of Mechanical Engineers

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Molecular dynamics simulations are carried out in order to investigate the saturation pressure of the water molecules in nanocylinder and to verify the Kelvin equation. Water molecules represented by the TIP4P/2005 model are confined in the nanocylinders whose diameters are 2.2 nm to 5.2 nm. The Lennard-Jones (LJ) potential is employed to model the interaction between a water molecule and a wall atom. The hydrophobic, intermediate, and hydrophilic nanocylinders with different LJ energy parameter are constructed. All of the systems are equilibrated by the constant temperature method in 1 ns. For the nanocylinders with the diameter of 2.2 nm, the Kelvin equation as the function of the temperature is qualitatively consistent to the MD results. When the temperature is fixed to 400 K, the Kelvin equation quantitatively coincides to the MD results for the nanocylinders with the diameter of 4.2 and 5.2 nm in the case of the intermediate and hydrophilic nanocylinders. The discrepancy increases with the decrease of the diameter to 2.2 nm. In the case of the hydrophobic nanocylinder, the Kelvin equation underestimates the saturation pressure.
J0610102 Oxygen permeability in ionomer on catalyst layer

KURIHARA Yuya, MABUCHI Takuya, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2014　"J0610102-1"-"J0610102-4"　2014/09/07
Publisher: The Japan Society of Mechanical Engineers

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Using two different types of ionomers which are composed of Nafion and hydrocarbon (HC), we constructed systems of the ionomers on Pt catalyst surface, and investigated water content dependence on oxygen permeability in the ionomers using molecular dynamics simulations. We have found that the oxygen permeability of the Nafion-based ionomer is better than that of the HC-based ionomer. Moreover, the number of permeated oxygen molecules decreases as water content increases in the both ionomers. Additionally, we analyzed density distributions of the ionomer components and oxygen, and solubility distributions of oxygen in the ionomers. As the results, in the ionomer-Pt interface of the Nafion-based ionomer, the pathways for oxygen permeation, that are voids in the ionomer, decrease with increasing the solvent molecules because the voids are occupied by the solvent molecules. On the other hand, in the ionomer-Pt interface of the HC-based ionomer, the solvent molecules accumulate on the surface of high-density polymers and block the pathways of oxygen.
Analyses of the Characteristics of Transport Phenomena of Reaction Materials in PEFC by Large Scale Molecular Dynamics Simulations

13　(3)　20-26,1　2014
Publisher: 燃料電池開発情報センター
ISSN： 1346-6623
523 Molecular Dynamics Study for the Transport Phenomena of Oxygen in Primary Pores of Catalyst Layer in Polymer Electrolyte Fuel Cell

Deguchi Masashi, Fukushima Akinori, Tuboi Nobuyuki, Tokumasu Takashi

2014　(67)　"523-1"-"523-2"　2014
Publisher: The Japan Society of Mechanical Engineers
高応答性流体の異分野融合展開

石本淳, 西山秀哉, 高奈秀匡, 徳増崇, 寒川誠二, 久保田智広, SAITO Kozo, 姫野武洋, 新城淳史, 岡村崇弘, 松浦一雄, 井上元

東北大学流体科学研究所共同利用・共同研究拠点流体科学研究拠点活動報告書　2013　2014
6PM1-D-2 A Molecular Dynamics Study of Proton Transport mechanism in Polymer Electrolyte Membrane

Mabuchi Takuya, Tokumasu Takashi

2013　(5)　151-152　2013/11/04
Publisher: The Japan Society of Mechanical Engineers

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We have performed an atomistic analysis of the transport of hydronium ions and water molecules in the nanostructure of hydrated Nafion membrane by systematically changing the hydration level using classical molecular dynamics simulations. The new empirical valence bond (EVB) model is developed based on the previous study of EVB model reported by Walbran et al. in order to improve the description of proton mobility in both aqueous and Nafion environments. A large contribution of Grotthuss mechanism for the diffusion of hydronium ions has been found at high water contents and this implies the important impact of Grotthuss mechanism in the membrane as well as in the bulk aqueous solutions.
J053016 New formulation of dissipative particle dynamics : Non-Markovian models

YOSHIMOTO Yuta, MIMA Toshiki, FUKUSHIMA Akinori, KINEFUCHI Ikuya, TOKUMASU Takashi, TAKAGI Shu, MATSUMOTO Yoichiro

Mechanical Engineering Congress, Japan　2013　"J053016-1"-"J053016-5"　2013/09/08
Publisher: The Japan Society of Mechanical Engineers

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We derive the equation of motion for non-Markovian dissipative particle dynamics (NMDPD) by introducing the history effects on the time evolution of the system. Our formulation is based on the generalized Langevin equation, which describes the motions of the centers of mass of clusters comprising microscopic particles. The mean, friction, and fluctuating forces in the NMDPD model are directly constructed from an underlying molecular dynamics (MD) system without any scaling procedure. For the validation of our formulation, we construct NMDPD models from high-density Lennard-Jones systems, in which the typical time scales of the coarse-grained particle motions and the fluctuating forces are not folly separable. The NMDPD models reproduce the temperatures and diffusion coefficients of the corresponding MD systems more accurately than the dissipative particle dynamics models based on a Markovian approximation. Our results suggest that the NMDPD method is a promising alternative for simulating mesoscale flows where a Markovian approximation is not valid.
J053012 A Molecular Dynamics Analysis of Quantum Effect on the Mechanism of Thermodynamic and Transport Properties of Cryogenic Hydrogen

NAGASHIMA Hiroki, TSUDA Shinichi, TSUBOI Nobuyuki, KOSHI Mitsuo, HAYASHI Koichi, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2013　"J053012-1"-"J053012-4"　2013/09/08
Publisher: The Japan Society of Mechanical Engineers

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In this study, we conducted analysis of quantum effect of the hydrogen molecules on the p-V-T relation of cryogenic hydrogen using classical Molecular Dynamics (MD) and path integral Centroid MD (CMD) method. We performed MD simulation across a wide temperature region in the constant density and compared the pressure formulations of each method. In addition, we calculated the diffusion coefficient using Green-Kubo method. As a result, it was confirmed that classical MD cannot reproduce the experimental data in the low temperature region and underestimates the virial pressure compared to the CMD. Moreover, it was clarified that taking the quantum effect into account produces broader repulsive region and shallower the potential well. Because of this mechanism, the intermolecular interaction of hydrogen diminishes and the virial pressure increases. In addition, it was confirmed that the diffusivity increase compared with classical representation.
J053022 Molecular Dynamics Simulation for Vapor/Liquid Coexistence of Water Molecules in Nanopore

Mima Toshiki, Kinefuchi Ikuya, Yoshimoto Yuta, Fukushima Akinori, Tokumasu Takashi, Takagi Shu, Matsumoto Yoichiro

Mechanical Engineering Congress, Japan　2013　"J053022-1"-"J053022-4"　2013/09/08
Publisher: The Japan Society of Mechanical Engineers

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Molecular dynamics simulation was conducted in order to investigate the vapor-liquid coexistence of the water molecules in nanocylinder. In this research, the Lennard-Jones energy parameter between a water molecule and an atom of a wall was optimized so as to model the contact angle of the carbon material in the fuel cell. The TIP4P/2005 as the model of a water molecule was used; this model produces well the vapor-liquid coexistence line. All of the systems were equilibrated by Nose-Hoover constant temperature algorithm. The electrostatic interaction between water molecules was calculated through smooth particle mesh Ewald method. First, we equilibrated a water plug in the single-wall atomistic nanocylinder with the diameter of 2.66nm. Water molecules burst from an interface of the water plug in equilibration. Then, the equilibrium densities both in dense and dilute region ware sampled over 1 ns. The vapor-liquid coexistence curve of confined water is different from one of the bulk system: the critical temperature decreases and coexistence curve shrinks.
J061031 Molecular Dynamics Study of Oxygen Permeation of the Ionomer on Pt catalyst in PEFC cathode side Catalyst Layer

SUGAYA Yuta, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2013　"J061031-1"-"J061031-4"　2013/09/08
Publisher: The Japan Society of Mechanical Engineers

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Polymer electrolyte fuel cell (PEFC) is focused worldwide as the energy conversion device for next generation. However, it has never been popular because of high price and low efficiency. In Polymer electrolyte fuel cell cathode catalyst layer, an ionomer with which the catalyst is covered is very important on the point of transferring protons to the catalytic surface on the cathode side. On the other hand, it is said that ionomer interferes with oxygen permeation to the catalytic surface. The mechanism of oxygen permeation through the ionomer was not analyzed in detail because it is too small to research by experiment. Moreover molecular dynamics simulation of the catalyst layer and oxygen permeability has not yet researched. In this research, we constructed the system including hydrocarbon membrane, water molecule, oxonium ion and platinum surface by using molecular dynamics study, and researched about the effect of the water content of the ionomer on the structure of the ionomer and oxygen permeability.
J061032 Analysis of Water and Proton Transport in PEM by Molecular Dynamics Simulation

MABUCHI Takuya, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2013　"J061032-1"-"J061032-4"　2013/09/08
Publisher: The Japan Society of Mechanical Engineers

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We have performed an atomistic analysis of the vehicular transport of hydronium ions and water molecules in the nanostructure of hydrated Nafion membrane by systematically changing the hydration level using classical molecular dynamics simulations. The new empirical valence bond (EVB) model is developed based on the previous study of EVB model reported by Walbran et al. in order to improve the description of proton mobility in both aqueous and Nafion environments. In addition to determination of diffusion coefficients of hydronium ions and water molecules as a function of hydration level as a dynamical analysis calculated by mean square displacement, we have also calculated radial distribution functions of hydronium ions and water molecules around the first solvation shell of sulfonate groups for structural analysis. A large contribution of Grotthuss mechanism for the diffusion of hydronium ions has been found at λ= 6 and this implies the important impact of Grotthuss mechanism in the membrane as well as in the bulk aqueous solutions.
高応答性流体の異分野融合展開

石本淳, 西山秀哉, 高奈秀匡, 徳増崇, 寒川誠二, 久保田智広, SAITO Kozo, 姫野武洋, 新城淳史, 岡村崇弘, 松浦一雄, 井上元

東北大学流体科学研究所共同利用・共同研究拠点流体科学研究拠点活動報告書　2012　2013
OS1-2-8 A Study on the Density Fluctuation in Diatomic Fluid around the Critical Point Using Molecular Dynamics Method

Tomi Masato, Tsuboi Nobuyuki, Tsuda Shin-ichi, Tokumasu Takashi

2012　(4)　173-174　2012/10/21
Publisher: The Japan Society of Mechanical Engineers

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In this study, we performed the Molecular Dynamics (MD) simulation for the extraction of the density fluctuations around the critical points of 2-Center-Lennard-Jones (2CLJ) fluids, which depend on the internulear distance. As a result, it was confirmed that the density fluctuation forms a ridge as the local maximum value near the critical density, and this tendency was consistent with the experiment by the small-angle X-ray scattering (SAXS).
OS1-2-2 Analysis of gas transport in polymer electrolyte fuel cells using structure constructed from X-ray nano CT

Kinefuchi Ikuya, Oyama Junpei, Yokoyama Koji, Kubo Norio, Tokumasu Takashi, Matsumoto Yoichiro

2012　(4)　161-162　2012/10/21
Publisher: The Japan Society of Mechanical Engineers

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This paper describes the analysis of gas transport in micro porous layers of polymer electrolyte fuel cells based on the three-dimensional structure obtained from X-ray nano computed tomography (CT). The polygonal surface representation of the porous structure was constructed from the cross-sectional CT images using the marching tetrahedrons algorithm. The diffusion flux through the porous layer was evaluated by the direct simulation Monte Carlo method since the characteristic pore size is comparable to the mean free path of gas molecules. The numerical simulation well reproduces the experimentally observed pressure dependence of diffusion resistance originating from the coexistence of Knudsen and molecular diffusion mechanisms. The effect of porous media morphology on gas transport was examined by an analysis of the trajectories of transmitted molecules through the porous layer.
OS1-2-1 Large-scale Molecular Dynamics Simulations for Transport Phenomena of Materials in PEFC

Tokumasu Takashi

2012　(4)　159-160　2012/10/21
Publisher: The Japan Society of Mechanical Engineers

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In this paper, we report large-scale molecular dynamics (MD) simulations to analyze nanoscale flow phenomena in Polymer Electrolyte Fuel Cells (PEFC). In particular, transport phenomena of proton and water in a polymer electrolyte membrane (PEM) and oxygen permeability of ionomers in a catalyst layer (CL) were simulated and their characteristics are discussed. In the analysis of proton transfer in a PEM, the diffusion coefficients obtained by this simulation were consistent with the experimental data. In the analysis of oxygen permeability of ionomers, the dependence of water content on the permeability was estimated and the difference between ionomer and bulk membrane was clarified.
J053023 Influence of the Intermoleculer Spin-spin Interaction on the Thermodynamic Property of Oxygen

TSUDA Shinichi, KOSHI Mitsuo, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2012　"J053023-1"-"J053023-5"　2012/09/09
Publisher: The Japan Society of Mechanical Engineers

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In this paper, we have discussed the spin-spin interaction effect of oxygen based on the evaluation of the liquid-vapor coexistence line of oxygen, using the Monte Carlo (MC) calculations with an ab-initio potential for the quintet oxygen as a dimer (Bartolomei et al., J. Chem. Phys., 2008) and that with a semi empirical model by Aquilanti et al. (J. Am. Chem. Soc., 1999) for the triplet and the singlet oxygen. As a result, an important spin-spin interaction effect on the dense oxygen was qualitatively extracted.
J056031 Analysis of Transport Phenomena of Water and Proton in Hydrated Nation Membrane by Molecular Dynamics Method

MABUCHI Takuya, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2012　"J056031-1"-"J056031-3"　2012/09/09
Publisher: The Japan Society of Mechanical Engineers

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We have performed an atomistic analysis of the vehicular transport of hydronium ions and water molecules in the nanostructure of hydrated Nafion membrane by systematically changing the hydration level using classical molecular dynamics simulations. The models of Nafion membrane based on DREIDING force field with modification of torsion potential are proposed and validated by comparing the density, water diffusivity, and Nafion morphology with experimental data. The simulated final density agrees with experiment within 1.3 % for various water contents and the trends that density decreases with increasing hydration level are reproduced. In addition to determination of diffusion coefficients of liquid molecules as a function of hydration level for dynamical analysis, we have also implemented the cluster analysis of liquid molecules for structural insight. The cluster analysis provides insights into the network formation of water channel at water content I = 6. The diffusion coefficient of water molecules is found to be in good agreement with experimental data. The diffusion coefficient of hydronium ions has showed that general trends in the experimental data are reproduced although the classical models have the limitation of hydronium dynamics.
J053021 A Numerical Study for Transport Phenomena in Nanoscale Porous Media

OSHIMA Tomoya, YONEMURA Shigeru, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2012　"J053021-1"-"J053021-3"　2012/09/09
Publisher: The Japan Society of Mechanical Engineers

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Gas flows in porous media appear in various regions of engineering, e.g., catalytic converters and fuel cells. In order to improve performance of such devices, it is important to understand transport phenomena in porous media. In porous media with pores as small as a molecular mean free path, we need to consider molecular motions directly instead of treating gas flow as continuum and we also need to consider effects of complicated channels. Therefore, the direct simulation Monte Carlo (DSMC) method is suitable to solve transport phenomena in porous media. We considered gas flows driven by pressure gradient in porous media imitated by locating nano-scale spheres randomly, and performed numerical smulations of gas flow without any surface reaction to clarify transport phenomena in porous media. We investigated effects of pressure gradient, diameter of spheres, and porosity on gas flow rate.
J056033 Molecular Dynamics Study of Oxygen Permeation in the Ionomer on Pt Catalyst of PEFC

SUGAYA Yuta, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2012　"J056033-1"-"J056033-4"　2012/09/09
Publisher: The Japan Society of Mechanical Engineers

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Polymer electrolyte fuel cell (PEFC) is focused worldwide as the energy conversion device for next generation. However, it has never been popular because of high price and low efficiency. In Polymer electrolyte fuel cell cathode catalyst layer, an ionomer with which the catalyst is covered is very important on the point of transferring protons to the catalytic surface on the cathode side. On the other hand, it is said that ionomer interferes with oxygen permeation to the catalytic surface. The mechanism of oxygen permeation through the ionomer was not analyzed in detail because it is too small to research by experiment. Moreover molecular dynamics simulation of the catalyst layer and oxygen permeability has not yet researched. In this research, we constructed the system including Perfluorosulfonic Acid (PFSA) membrane, water molecule, oxonium ion and platinum surface by using molecular dynamics study, and researched about the effect of the water content of the ionomer on the structure of the ionomer and oxygen permeability.
J053033 An Analysis of Thermodynamic Properties of Cryogenic Hydrogen using Path Integral Centroid Molecular Dynamics Method

NAGASHIMA Hiroki, TSUDA Shin-ichi, TSUBOI Nobuyuki, KOSHI Mitsuo, HAYASHI Koichi, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2012　"J053033-1"-"J053033-4"　2012/09/09
Publisher: The Japan Society of Mechanical Engineers

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In this paper, we conducted analysis of thermodynamic properties of cryogenic hydrogen using classical Molecular Dynamics (MD) and path integral Centroid MD (CMD) method to understand an effect of quantum nature of hydrogen molecules. We performed NVE constant MD simulation across a wide density-temperature condition to obtain an Equation Of State (EOS). Simulation results were compared with experimental data. As a result, it was confirmed that classical MD cannot reproduce the experimental data at the high density region. On the other hand, CMD well reproduces the thermodynamic properties of liquid hydrogen. And it was also confirmed that the disagreements between classical MD and CMD results decrease with increase of temperature. Moreover we clarified that the quantum nature affects the virial term more than the kinetic one and makes the virial pressure larger than in classical mechanics.
高応答性流体の異分野融合展開

石本淳, 西山秀哉, 高奈秀匡, 徳増崇, 寒川誠二, 久保田智広, SAITO Kozo, 姫野武洋, 新城淳史, 岡村崇弘, 松浦一雄, 井上元

東北大学流体科学研究所共同利用・共同研究拠点流体科学研究拠点活動報告書　2011　2012
4-3 Molecular Dynamics Simulation of Proton Transfer in Polymer Electrolyte Membrane of PEFC

Tokumasu Takashi

2011　(3)　41-42　2011/09/25
Publisher: The Japan Society of Mechanical Engineers

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Proton transfer in polymer electrolyte membrane (PEM) was analyzed by molecular dynamic simulation considering both Vehicle and Grotthus mechanism. The empirical valence bond (EVB) method was used to treat Grotthus mechanism and the intermolecular potential used in this method was determined so that the energy barrier during proton hopping obtained by this potential is consistent with that obtained by Molecular Orbital (MO) calculation. A perfluorosulfonic acid (PFSA) membrane was used as the PEM. The transport phenomena of proton was simulated according to the water content and the detailed mechanism was analyzed paying attention to the nanoscale structure of fluid in the PEM, such as water cluster.
MP-1 A Molecular Dynamics Study on the Thermodynamic Estimation of Cryogenic Hydrogen

NAGASHIMA Hiroki, TOKUMASU Takashi, TSUDA Shin-ichi, TSUBOI Nobuyuki, KOSHI Mitsuo, HAYASHI A.Koichi

2011　(3)　69-70　2011/09/25
Publisher: The Japan Society of Mechanical Engineers

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In this paper, we conducted estimation of thermodynamic and transport properties of cryogenic hydrogen using classical Molecular Dynamics (MD) method. We applied three empirical potential models and one ab initio potential which was derived by Molecular Orbital (MO) calculation. We performed NVE constant MD simulation across a wide density-temperature condition to obtain Equation Of State (EOS) and transport coefficients. Simulation results were compared with experimental data using the principle of corresponding states. As a result, it was confirmed that the effect of intermolecular interaction on the principle of corresponding states is small and cannot reproduce the experimental data at the high density region. This distinction is considered to arise from the quantum effect of actual liquid hydrogen.
MP-4 Molecular dynamics study of the water dynamics in the micro pore of the graphite

Fukushima Akinori, Tokumasu Takashi

2011　(3)　75-76　2011/09/25
Publisher: The Japan Society of Mechanical Engineers

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In this study, we focus on the transport property of water droplet in the nano hydrophobic pore. We report the size dependence of the transport property of water droplet in a nano slit pore. Considering the several models of the nano pores, we show the differences of the structures of water droplets and discuss these differences from the viewpoints of the interaction between hydrophobic walls. Furthermore, we evaluate forces by the hydrophobic walls and show the difference of the transport property using the mechanical coefficients, such as friction coefficient. From these results, we clarify the dependence of the width of pore on the static and dynamic properties of the water droplet.
MP-5 Molecular dynamics study for the phenomena of proton hopping considering the effect of surrounding water molecules

Sakai Hironori, Yoshida Taiki, Tokumasu Takashi

2011　(3)　77-78　2011/09/25
Publisher: The Japan Society of Mechanical Engineers

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The purpose of this study is the development of proton(s) hopping rate by applying new model for Molecular Dynamics (MD) calculation with Empirical Valence Bond (EVB) method. The overview about this new model is an acceptor selection method based on energy prediction instead of the one based on distance. The effect of water molecules outside the Eigen cation was mainly considered in this new model. Then, energy prediction and comparison to presumed hopped states were performed to determine the acceptor. After energy prediction, the water for the lowest energy state was chosen as the proton acceptor. In this model, the microenvironment interaction to the formation of the cluster and proton hopping were reasonably expressed as an actual condition. This procedure was applied for proton hopping.
S053011 Molecular Dynamics Study of Oxygen Diffusion in the Ionomer of PEFC catalyst layer

SAKAI Kiminori, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2011　"S053011-1"-"S053011-4"　2011/09/11
Publisher: The Japan Society of Mechanical Engineers

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In the Polymer electrolyte membrane fuel cell (PEFC) cathode catalyst layer, the structure of ionomer with which the catalyst is covered is very important on the point of transferring protons to the catalytic surface and oxygen permeation to the surface. But the mechanism of oxygen permeation through an ionomer was not analyzed in detail because it is too small to research by experiment. Moreover molecular dynamics simulation of the catalyst layer and oxygen permeability has not yet researched. In this research, we constructed the system including PFSA membrane, water, oxonium ion and platinum layers by using molecular dynamics study and researched about the effect of the water content of the ionomer on the structure of the ionomer and the permeability of the oxygen molecule. As the result, we found that PFSA and water molecule gathered on the platinum catalyst surface, the oxygen permeability decreased as water content rate increased in the ionomer.
S053022 Analysis of Proton and Water Transferring Property within Polyelectrolyte Membrane in PEFC

MABUCHI Takuya, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2011　"S053022-1"-"S053022-3"　2011/09/11
Publisher: The Japan Society of Mechanical Engineers

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Protons transfer in polyelectrolyte membrane by both Vehicle and Grotthus mechanism. Grotthus mechanism hasn't been broadly researched because of its complexity. This paper analyzes proton transfer behavior in Nafion membrane using MD simulation with both Vehicle and Grotthus mechanism. To treat Grotthus mechanism, Empirical Valence Bond (EVB) method is used. Also, distribution of water molecules in the membrane is an important factor that improves the efficiency of the PEFC. Therefore, water transfer behavior caused by electro-osmotic flow in the membrane is calculated by replicating electro-osmotic flow with constant barycentric velocity of oxonium ions. The both simulation results describe the structure and transport property of oxonium ions and water molecules.
S053014 Molecular dynamics study for the diffusion phenomena of proton considering proton hopping

SAKAI Hironori, YOSHIDA Taiki, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2011　"S053014-1"-"S053014-3"　2011/09/11
Publisher: The Japan Society of Mechanical Engineers

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The aim of this study is refinement of proton(s) hopping rate by applying new model for Molecular Dynamics (MD) calculation with Empirical Valence Bond (EVB) method. The overview about this new model is an acceptor selection method based on energy prediction instead of the one based on distance. The effect of water molecules outside the Eigen cation was mainly considered in this new model. Then, energy estimation and comparison to presumed hoping states were done before acceptor selection. After energy estimation, the water for lower energy state was chosen as the proton acceptor. In this model, the microenvironment interaction to the formation of the cluster and proton hopping were reasonably expressed as an actual condition. This procedure was applied for proton hopping. The total number of cluster formation and cancel were also analyzed.
S053024 Multi-scale Observation on Membrane Electrode Assembly by Using Polarization Analysis Neutron Small-Angle Scattering, Scanning Electron Microscopy and Computer Simulation.

KOIZUMI Satoshi, KAWAKATSU Toshihiro, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2011　"S053024-1"-"S053024-3"　2011/09/11
Publisher: The Japan Society of Mechanical Engineers

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In order to perform a multi-scale observation on a membrane-electrolyte assembly (MEA) of polymer electrolyte fuel cell (PEFC), small-angle neutron scattering (SANS) was recently reinforced by advanced neutron optics. A focusing ultra-small-angle scattering method was developed by using a neutron lens, which is made of a single crystal MgF2. By combining a double crystal (Bonse-Hart) method, we are able to reach to 10 p.m length scale, which corresponds to the size of aggregation by carbon powders in an electrode layer. Polarization analysis enables us to selectively remove incoherent scattering from hydrogen atoms and to detect coherent scattering due to ion-cluster of polymer electrolyte (Nafion) and water distribution in it. In order to output structural information in real space, we examined our SANS results by comparing images in real space obtained by low vacuum SEM and multi-scale computer simulations
J054052 An Analysis of Thermodynamic Property of Cryogenic Hydrogen using Classical Molecular Simulation

NAGASHIMA Hiroki, TOKUMASU Takashi, TSUDA Shin-ichi, TSUBOI Nobuyuki, KOSHI Mitsuo, HAYASHI Koichi

Mechanical Engineering Congress, Japan　2011　"J054052-1"-"J054052-4"　2011/09/11
Publisher: The Japan Society of Mechanical Engineers

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We conducted an analysis of thermodynamic property of cryogenic hydrogen using classical molecular dynamics. Especially, we investigated the effect of intermolecular potential model on thermodynamic and transport properties of cryogenic hydrogen. We applied three empirical potential models and one ab initio potential which was derived by Molecular Orbital (MO) calculation. We performed NVE constant Molecular Dynamics (MD) calculation to obtain Equation Of State (EOS). Moreover, we investigated transport coefficients (viscosity coefficient, diffusion coefficient and thermal conductivity) using Green-Kubo method. Simulation results were compared with NIST data using the principle of corresponding state. As a result, it was confirmed that every potential showed the same tendency and cannot reproduce NIST data at the high density region.
J054022 A Numerical Study for Nanoscale Gas Flow in Porous Media

TOMARIKAWA Ko, OSHIMA Tomoya, YONEMURA Shigeru, TOKUMASU Takashi

Mechanical Engineering Congress, Japan　2011　"J054022-1"-"J054022-5"　2011/09/11
Publisher: The Japan Society of Mechanical Engineers

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In porous media with holes as small as a molecular mean free path, Knudsen number of gas flow in the narrow channel is in the order of unity. Therefore, the direct simulation Monte Carlo (DSMC) method is suitable to solve the transport phenomena in porous media. However, even if the inside structures of porous media are measured transparently by microscopy technique such as 3D transmission electron microscopy (3D TEM), geometries obtained will be discrete. Moreover, performing DSMC simulation for nanoscale gas flow in porous media is difficult because of its complicated structure. Therefore, we need to estimate and simplify the real shapes of complicated channels inside porous media. In this work, we propose two schemes for estimation and simplification of solid bodies in porous media. In the first scheme, we simplify them as aggregations of cubes. In the second scheme, we simplify them as aggregations of polyhedra. We put cubes or polyhedra based on the discrete information of solid bodies in porous media. We examine merits and demerits of these schemes by performing numerical simulations of example problems.
J054043 A Validation of the Accuracy of Cubic Equation of State for Hydrogen/Oxygen Mixture System

TOMI Masato, TSUDA Shinichi, TSUBOI Nobuyuki, TOKUMASU Takashi, KOSHI Mitsuo

Mechanical Engineering Congress, Japan　2011　"J054043-1"-"J054043-4"　2011/09/11
Publisher: The Japan Society of Mechanical Engineers

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Combustion conditions in liquid rocket engines using oxygen-hydrogen propellant change in the wide region of temperatures and pressures. This combustion is greatly affected by the complex flow-field of oxygen and hydrogen near the injections in the combustion chamber. CFD is often used to understand the flow-field, but, equation of state that required for CFD has many unclear parts. Therefore, in this study, the accuracy of cubic type of equation of state focus on specific heat at constant volume and pressure against oxygen hydrogen mixture system was evaluated by using the molecular dynamics with ab initio potential by Koshi et al. As a result, Soave-Redlich-Kwong (SRK) equation of state with a conventional classical mixing rule showed good agreements with our calculation results for pressure-volume-temperature relationship, at least in the present conditions for oxygen-hydrogen mixture gases.
0307 Interfacial tension of water transporting in graphite nano pore

HAMADA Yoshinobu, TOKUMASU Takashi

Fluids engineering conference ...　2010　111-112　2010/10/29
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-2882

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In this research, we reported the dependence of pore size on the characteristics of transport phenomena of confined water in a nano slit pore by molecular dynamics (MD) simulation. The two surfaces were made of graphite, whose distance was set at 15 and 30 Å. The interaction potential between water and carbon was Lennard-Jones potential, and that between water molecules was SPC/E. The water formed a film in each system. The film moved when pressure gradient parallel to the walls was given to water molecules in the pore. From the results, we examined dependence of the velocity of water in the slit pores on pore width.
0309 The Limit of Classical Method on the Molecular Simulation of Cryogenic Hydrogen

NAGASHIMA Hiroki, TOKUMASU Takashi, TSUDA Shinichi, TSUBOI Nobuyuki, HAYASHI A. Koichi

Fluids engineering conference ...　2010　115-116　2010/10/29
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-2882

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In this paper, we clarified the limit of classical method on the molecular simulation of cryogenic hydrogen. We applied three empirical potential models and one ab initio potential which was derived by Molecular Orbital (MO) calculation. We performed NVE constant Molecular Dynamics (MD) simulation across a wide density-temperature condition to obtain Equation Of State (EOS). Simulation results were compared with NIST data using the principle of corresponding states. As a result, it was confirmed that the effect of intermolecular interaction on the principle of corresponding states is small and cannot reproduce NIST data at the high density region. This distinction is considered to arise from the quantum effect of actual liquid hydrogen.
0303 Oxygen diffusion in ionomer of PEFC cathode side catalyst layer

SAKAI Kiminori, TOKUMASUI Takashi

Fluids engineering conference ...　2010　103-104　2010/10/29
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-2882

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The mechanism of oxygen permeation through an ionomer of polymer electrolyte membrane fuel cell (PEFC) was not analyzed in detail and it is too difficult to research by experiment. Moreover molecular dynamics simulation of the structure of catalyst layer and oxygen permeability has not yet reserched. We made the system including nafion, water, oxonium ion, nanoparticle platinum on a carbon layer by using molecular dynamics study, and researched about the structure of ionomer and the permeability of the oxygen molecule.
0302 Molecular Dynamics Study on Proton Conduction including Grotthus Mechanism in Polyelectrolyte Membrane

Yoshida Taiki, Tokumasu Takashi

Fluids engineering conference ...　2010　101-102　2010/10/29
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-2882

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In this study, the property of proton transfer in Nafion membrane was analyzed by molecular dynamics (MD) simulation including both Vehicle and Grotthus mechanism. To treat Grotthus mechanism, Empirical Valence Bond (EVB) method was introduced to MD simulation. The potential energy barrier of proton hopping obtained by EVB method was adjusted to the computational result of Density Functional Theory (DFT). After adjusting EVB potential, it is confirmed that protons hop along the hydrogen bond network consecutively. The parameter for the simulation of Nafion membrane was water contents λ, which is defined as the ratio of water molecules and hydronium ions to sulfo groups, SO_3^-, obtained by λ=N_<H2O,H3O+>/N_<SO3->. The changes of transferring properties and structure of molecules with the changes of λ were analyzed by Mean Square Displacement and Radial Distribution Function, respectively.
0301 Proton transport in hydrogen bond network of confined water

Miyoshi Nobuya, Kinefuchi Ikuya, Tokumasu Takashi, Takagi Shu, Matsumoto Yoichiro

Fluids engineering conference ...　2010　99-100　2010/10/29
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-2882

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In this paper, we present molecular dynamics study of the fast proton transport in water confined between hydroxylated silica surfaces. Empirical valence bond (EVB) method was introduced to our MD simulation system for reproducing Grotthuss mechanism (proton hopping). We evaluated the enhancement of Grotthuss mechanism by counting the number of hopping events in confined and bulk water. The number in confined water increases by 4-6 times compared to bulk value, suggesting the enhancement of proton transport. Furthermore, the activation energy of Grotthuss mechanism was calculated from Arrhenius plot for the number of hopping events. As a result, the activation energy decreases from 4.5 kcal/mol in bulk water to 3.4 kcal/mol in confined water, which leads to the fast proton motion.
MNM-P4-2 Proton transport in hydrogen bond network of confined water

Miyoshi Nobuya, Kinefuchi Ikuya, Tokumasu Takashi, Takagi Shu, Matsumoto Yoichiro

2010　(2)　87-88　2010/10/12
Publisher: The Japan Society of Mechanical Engineers

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In this paper, we present molecular dynamics study of the fast proton transport in water confined between hydroxylated silica surfaces. Empirical valence bond (EVB) method was introduced to our MD simulation system for reproducing Grotthuss mechanism (proton hopping). We counted the number of hopping events in bulk and confined water and found that the hopping frequency in the first layer of water (less than 6 Å from the interface) increases by 4-6 times compared to bulk value, suggesting the enhancement of proton transport. Furthermore, the activation energy of Grotthuss mechanism was calculated from Arrhenius plot for the number of hopping events. As a result, the activation energy decreases from 4.5 kcal/mol in bulk water to 3.4 kcal/mol in confined water, which leads to the fast proton motion.
A Study of Proton Conductivity of Polymer Electrolyte Membrane Including Proton Hopping

Tokumasu Takashi, Yoshida Taiki

2010　109-109　2010
Publisher: 日本流体力学会

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This study describes the proton conductivity of Nafion membrane analyzed by molecular dynamics (MD) simulation including both Vehicle and Grotthus mechanism. To treat Grotthus mechanism, Empirical Valence Bond (EVB) method was introduced to MD simulation. The potential energy barrier of proton hopping obtained by EVB method was adjusted to the computational result of Density Functional Theory (DFT). After adjusting EVB potential, it is confirmed that protons hop along the hydrogen bond network consecutively. The parameter for the simulation of Nafion membrane was water contents λ, which is defined as the ratio of water molecules and hydronium ions to sulfo groups, SO_3^-, obtained by λ=N_<H2O,H3O+>/N_<SO3->. The changes of transferring properties and structure of molecules with the changes of λ were analyzed by Mean Square Displacement and Radial Distribution Function, respectively.
金属表面における気体分子の解離現象の数値解析

徳増崇

日本機械学会流体工学部門ニューズレター　2008/09
Publisher: 日本機械学会
統合化計算化学手法による燃料電池材料設計 - 第4回：電子状態を考慮した分子動力学法の基礎と燃料電池触媒反応現象解析への応用 -

徳増崇, 坪井秀行, 古山通久, 遠藤明, 久保百司, Carlos A. Del Carpio, 宮本明

燃料電池　5　(4)　111-116　2006/04
Simulation of dissociative adsorption of H2 on catalyst of fuel cell

The Memoirs of the Institute of Fluid Science,Tohoku University　17　45-52　2006
Publisher: 東北大学流体科学研究所
ISSN： 0916-2860
Observation of cavitation in cryogenic inducer based on unsteady pressure measurements

KIKUTA Kengo, HASEGAWA Satoshi, SHIMAGAKI Mitsuru, NAKAMURA Noriaki, TOKUMASU Takashi, YOSHIDA Yoshiaki

Fluids engineering conference ...　2004　34-34　2004/11/24
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-2882

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For experimantally investigation of themodynamic effect on cavitation, it is of value to observe the cavitation in cryogenic flow, but the visualization is difficult. For this reasen, we tried to estimate the cavitating region in liquid nitrogen based on unsteady pressure distribution. Unsteady pressure was measured by placing sensors on casing of inducer. By this method, it succeeded in grasping of the cavitating rejion in relation to cavitation number. The comparison of the expriments in liquid nitrogen and in cold water allowed us to estimate theamplitude of the themodynamic effect. Consequently, it turns out that the amplitude of themodynamic effectis changing with the cavity length. The amount of temperature depression increases rapidly when the cavity extends over the throat.
熱流体工学における分子動力学法(第4回)

徳増崇, 小原拓

日本数値流体力学会誌　10　(1)　41-46　2002/02
Molecular Dynamics in Thermofluid Engineering

Takashi Tokumasu, Taku Ohara

日本数値流体力学会誌,日本数値流体力学会　10　41-46　2002
熱流体工学における分子動力学法(第3回)

徳増崇, 小原拓

日本数値流体力学会誌　9　(5)　177-182　2001/11
201 The effect of internal degree of freedom on the nucleation of bubble

TOKUMASU Takashi, KAMIJO Kenjiro, MATSUMOTO Yoichiro

Fluids engineering conference ...　2001　25-25　2001/09/28
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-2882
811 OBSERVATION OF CRYOGENIC TWO-PHASE FLOW IN A PIPE

ONISHI Masahiro, OIKE Mamoru, TOKUMASU Takashi, KAMIJYO Kenjiro

Fluids engineering conference ...　2001　110-110　2001/09/28
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-2882
810 Molecular Dynamics Study of Heterogeneous Bubble Nucleation in Binary Mixture Liquid Oxygen

Tsuda Shinichi, Tokumasu Takashi, Kamijo Kenjiro, Matsumoto Yoichiro

Fluids engineering conference ...　2001　109-109　2001/09/28
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-2882
熱流体工学における分子動力学法(第2回)

徳増崇, 小原拓

日本数値流体力学会誌　9　(4)　122-127　2001/08
熱流体工学における分子動力学法(第1回)

徳増崇, 小原拓

日本数値流体力学会誌　9　(3)　89-94　2001/05
(11)二原子分子衝突モデルの構築に関する研究

徳増崇

日本機械学會誌　103　(978)　296-296　2000/05/05
Publisher: 一般社団法人日本機械学会
ISSN： 0021-4728
Molecular Dynamics Simulation of Bubble Generation in Liquid Oxygen

TOKUMASU Takashi, MATSUMOTO Yoichiro, KAMIJO Kenjiro, OIKE Mamoru

18　335-336　1999/07/29

ISSN： 1342-8004

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Books and Other Publications 3

Molecular Dynamics - Theroretical developments and applications in nanotechnology and energy - Charter 15

Takashi Tokumasu

2012
Charter 5, Multi-scale Analysis of Flow Phenomena Including Surface Reactions

Takashi Tokumasu

Tohoku University Press　2008/03
数値流体力学ハンドブック

徳増崇, 崎山幸紀

2003/04

Presentations 195

粗視化分子動力学法を用いた水・アルコール混合溶液中におけるアイオノマー凝集現象の解析

馬渕拓哉, 徳増崇

第32回数値流体力学シンポジウム　2018/12/11
PEFC触媒層における酸素分子拡散機構の分子論的解析

中内将隆, 馬渕拓哉, 吉本勇太, 金子敏弘, 杵淵郁也, 武内秀樹, 徳増崇

第32回数値流体力学シンポジウム　2018/12/11
Scattering Properties of Gas Molecules on Water Adsorbed Surfaces in High Knudsen Number Flows International-presentation

Naoya Uene, Hideki Takeuchi, Yasutaka Hayamizu, Takashi Tokumasu

the 21st Australasian Fluid Mechanics Conference　2018/12/11
Thermodynamic Property Gradients in Near-Surface Water Thin Film International-presentation

Manish Gupta, An Zou, Takashi Tokumasu, Shalabh C. Maroo

18th International Symposium on Advanced Fluid Information　2018/11/07
Molecular Dynamics Simulation on Dispersion of hBN Nano Particles in TMP Ester Based Bio-lubricants International-presentation

Rizky Ruliandini, Nasruddin, Takashi Tokumasu

18th International Symposium on Advanced Fluid Information　2018/11/07
Analysis of Transport Phenomena of Oxygen Ion in Dual-phase Electrolyte Material International-presentation

Hiroki Nagashima, Ryan Falkenstein-Smith, Vincent DeBiase, Jeongmin Ahn, Takashi Tokumasu

18th International Symposium on Advanced Fluid Information　2018/11/07
Theoretical Optimization of Epitaxial Magnesium Oxide Film on Silicon Substrate International-presentation

Satoru Kaneko, Manabu Yasui, Masahito Kurouchi, Rieko Sudo, Tamio Endo, Shigeo Yasuhara, Yoshimi Nakamaru, Chiemi Kokubun, Kayoko Konda, Takashi Tokumasu

18th International Symposium on Advanced Fluid Information　2018/11/07
Statistical Mechanical Evaluation of Thermophysical Properties of Oxygen-hydrogen Mixture System Based on the Differential Hierarchy of a Complete Thermodynamic Function International-presentation

Ryuji Takahashi, Nobuyuki Tsuboi, Takashi Tokumasu, Shin-ichi Tsuda

18th International Symposium on Advanced Fluid Information　2018/11/07
Molecular Dynamics Simulation of Oxygen Diffusion on Ionomer Surface International-presentation

Masataka Nakauchi, Takuya Mabuchi, Yuta Yoshimoto, Toshihiro Kaneko, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

18th International Symposium on Advanced Fluid Information　2018/11/07
Molecular Dynamics Simulation of a Nano Droplet in a nm-order Channel International-presentation

Akinori Fukushima, Nicolas Fillot, Takashi Tokumasu, Philippe Vergne

18th International Symposium on Advanced Fluid Information　2018/11/07
A Molecular Dynamics Study for Scattering Properties of Gas Molecules on Water Adsorbed Surface International-presentation

Naoya Uene, Hideki Takeuchi, Yasutaka Hayamizu, Takashi Tokumasu

15th International Conference on Flow Dynamics　2018/11/07
Large Scale Molecular Simulations of Mass Transport Phenomena in PEFC International-presentation Invited

Takashi Tokumasu, Takuya Mabuchi

15th International Conference on Flow Dynamics　2018/11/07
Mechanical Behavior of Hydrated Polymers at Nanoscale from Elasticity to Rupture International-presentation

William Gonçalves, Takuya Mabuchi, Takashi Tokumasu

the 9th International Conference on Multiscale Materials Modeling　2018/10/28
液体水素の量子性を考慮した密度汎関数理論による気泡核生成速度の評価

安井大貴, 永島浩樹, 徳増崇, 渡邊聡, 津田伸一

第19回キャビテーションに関するシンポジウム　2018/10/18
Quantum Effect on Proton Diffusion in BaZrO3 Membrane International-presentation

Hiroki Nagashima, Takashi Tokumasu

234th ECS Meeting, Cancun　2018/09/30
Molecular Dynamics Study of the Thickness Dependence of Structure and Mass Transport in Ionomer Thin Film International-presentation

Koichi Kobayashi, Takuya Mabuchi, Gen Inoue, Takashi Tokumasu

234th ECS Meeting　2018/09/30
Ionomer and Carbon Aggregate Structure in Catalyst Ink Using Coarse-Grained Molecular Dynamics Simulations International-presentation

Takuya Mabuchi, Takashi Tokumasu

234th ECS Meeting　2018/09/30
Kinetic Analysis of Oxygen Transport Phenomena through Ionomer Thin Film on Pt Surface in PEFC International-presentation

Yuya Kurihara, Takuya Mabuchi, Takashi Tokumasu

234th ECS Meeting　2018/09/30
分子シミュレーションによる燃料電池内部の水和状態と物質輸送特性の相関の解析 International-presentation Invited

TOKUMASU Takashi

日本分析化学会第67年会　2018/09/14
炭化水素系イオン交換膜の分子動力学による特性解析

幸田啓太郎, 徳増崇, 福島啓悟

第12回分子科学討論会　2018/09/10
速度論を考慮したPEFCアイオノマー薄膜の酸素透過性に関する分子動力学解析

栗原祐也, 馬渕拓哉, 徳増崇

日本機械学会2018年度年次大会　2018/09/10
酸水素混合系の音速に対する古典的混合則の精度検証

高橋竜二, 坪井伸幸, 徳増崇, 津田伸一

日本機械学会2018年度年次大会　2018/09/10
高クヌッセン流れにおける固体壁面での反射境界条件の検討（吸着水分子が気体分子散乱特性に及ぼす影響）

上根直也, 武内秀樹, 早水康隆, 徳増崇

日本機械学会2018年度年次大会　2018/09/10
アイオノマー膜表面における酸素分子表面拡散現象の分子論的解析

中内将隆, 馬渕拓哉, 堀琢磨, 吉本勇太, 杵淵郁也, 武内秀樹, 徳増崇

日本機械学会2018年度年次大会　2018/09/10
粗視化分子動力学法を用いた触媒インク中におけるアイオノマー分散構造の解析

馬渕拓哉, 徳増崇

日本機械学会2018年度年次大会　2018/09/10
数値計算を用いたナノ液滴接触線近傍における摩擦現象の解析

福島啓悟, 徳増崇

日本機械学会2018年度年次大会　2018/09/10
Quantum Effect on Proton Diffusion in BaZrO3 Membrane International-presentation

Hiroki Nagashima, Takashi Tokumasu

234th ECS Meeting, Cancun　2018/09/03
Ionomer Aggregate Structure in Water/Alcohol Solutions Using Coarse-Grained Molecular Dynamics International-presentation

Takuya Mabuchi, Takashi Tokumasu

69th Anuual Meeting of the International Society of Electrochemistry　2018/09/02
Quantum Effects of Hydrogen on Thermal Transport Properties of Liquid Hydrogen International-presentation

Hiroki Nagashima, Shin-ichi Tsuda, Takashi Tokumasu

CALCON-ICCT 2018　2018/08/05
Gas-surface Dynamics of Oxygen Molecules on Nafion Ionomer Membrane International-presentation

Masataka Nakauchi, Takuya Mabuchi, Takuma Hori, Yuta Yoshimoto, Ikuya Kinefuchi, Hideki Takeuchi, Takashi Tokumasu

31st International Symposium on Rarefied Gas Dynamics　2018/07/23
Ionomer and Carbon Aggregations in Water/Alcohol Solutions by Coarse-Grained Molecular Dynamics International-presentation

Takuya Mabuchi, Takashi Tokumasu

Grand Renewable Energy 2018 International Conference and Exhibition　2018/06/17
Nanoscale Transport Phenomena of Reaction Materials in Polymer Electrolyte Fuel Cell International-presentation Invited

Takashi Tokumasu

19th World Congress on Material Science and Engineering　2018/06/13
固体高分子形燃料電池材料の物質輸送・構造特性に関する分子論的解析 Invited

徳増崇

高分子学会水素・燃料電池材料研究会　2018/06/08
粗視化分子動力学法を用いた水・アルコール混合溶液中におけるアイオノマー分散現象の解析

馬渕拓哉, 徳増崇

第55回日本伝熱シンポジウム　2018/05/29
分子動力学法による酸水素混合系の拡散係数評価

永島浩樹, 津田伸一, 徳増崇

第55回日本伝熱シンポジウム　2018/05/29
PEFCの物質輸送特性と構造特性の相関に関する分子論的研究

徳増崇, 馬渕拓哉

第25回燃料電池シンポジウム　2018/05/17
触媒インク中のアイオノマー分散構造に関する分子論的解析

馬渕拓哉, 徳増崇

第25回燃料電池シンポジウム　2018/05/17
MDシミュレーションを用いたアイオノマー薄膜の構造およびプロトン輸送の解析

小林光一, 馬渕拓哉, 徳増崇

第25回燃料電池シンポジウム　2018/05/17
固体高分子形燃料電池ナノ構造体内部の流れの数値解析 Invited

徳増崇

日本機械学会RC277研究分科会「流れの数値解析と実験計測の双方向連携に関する研究分科会」　2018/04/16
二成分Lennard-Jones流体における対応状態原理の成立性

高橋竜二, 坪井伸幸, 徳増崇, 津田伸一

日本機械学会九州支部第71期総会・講演会　2018/03/16
AN ANALYSIS OF QUANTUM EFFECT ON THE THERMODYNAMIC PROPERTIES OF CRYOGENIC HYDROGEN International-presentation

The third International Forum on Heat Transfer　2012/11/13
ナノ液柱の運動量輸送特性に関する分子動力学的解析

第4回マイクロ・ナノ工学シンポジウム　2012/10/22
PEFC内物質輸送現象に関する大規模分子動力学シミュレーション

第4回マイクロ・ナノ工学シンポジウム　2012/10/22
Nanoscale Transport Phenomena in PEM of PEFC by Large Scale Molecular Dynamics Simulations International-presentation

222th ECS Meeting　2012/10/07
Nano-Scale Modeling of Confined Liquid Films and Bridges International-presentation

The ninth International Conference on Flow Dynamics　2012/09/19
A Molecular Dynamics Study of Lubrication Phenomena of a Liquid Bridge International-presentation

The 26th International Conference on Surface Modification Technologies　2012/07/10
A Molecular Dynamics Study of Lubrication Characteristics of Nanoscale Liquid Bridge

The 15th Nordic Symposium on Tribology　2012/06/13
PEFC内部の物質輸送現象に関する大規模分子シミュレーション

第19回燃料電池シンポジウム　2012/05/16
Molecular Structure in PEM and Its Relation with Proton Diffusivity International-presentation

Proceedings of the Eighth KSME-JSME Thermal and Fluids Engineering Conference　2012/03/19
グラファイト微細孔内部における液滴の挙動に関する分子動力学計算

第25回数値流体力学シンポジウム　2011/12/21
多孔質体内の複雑流路を流れるナノ気体流れの数値解析

第25回数値流体力学シンポジウム　2011/12/21
分子動力学法によるPEFC高分子膜内におけるプロトン・水分子輸送特性の解析

第25回数値流体力学シンポジウム　2011/12/21
臨界点近傍における酸水素混合系の熱物性評価

第25回数値流体力学シンポジウム　2011/12/21
A Numerical Study for Nanoscale Gas Flow in Porous Media International-presentation

International Workshop on Micro/Nano-Engineering　2011/12/18
Molecular Dynamics Simulation of Nanoscale Flow Phenomena in PEFC International-presentation

International Workshop on Micro/Nano-Engineering　2011/12/18
固体高分子形燃料電池内部で生じる物質輸送現象の大規模分子シミュレーション

第11回インテリジェント・ナノプロセス研究会　2011/12/16
Molecular Dynamics Simulations of Nanoscale Flow Phenomena in Fuel Cell

Workshop on Micro-Nano Flow Engineering　2011/12/13
A Molecular Dynamics Study for Dissociation of H2 Molecule on Pt(111) Surface International-presentation

2011 International Conference on Mechanical Science and Engineering　2011/12/09
A Molecular Dynamics Study of Momentum Transport in a Nanoscale Liquid Bridge International-presentation

the Eleventh International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2011/11/10
Molecular Dynamics Study of Oxygen Permeation in the Ionomer on Pt Catalyst International-presentation

Eighth International Conference on Flow Dynamics　2011/11/10
Molecular Dynamics Study of Proton and Water Transfer in Polyelectrolyte Membrane International-presentation

Eighth International Conference on Flow Dynamics　2011/11/10
A molecular Dynamics study on the Thermodynamic Estimation of Cryogenic Hydrogen International-presentation

The Eighth International Conference on Flow Dynamics　2011/11
A Molecular Dynamics Study for the Lubrication Phenomena of Nanoscale Liquid Bridge International-presentation

International Tribology Conference Hiroshima 2011　2011/11/01
The Modeling of Nanoscale Flow Phenomena in Polymer Electrolyte Fuel Cell by Molecular Dynamics Method International-presentation

Nano-S&T 2011　2011/10/25
Analysis of Proton and Water Transfer in PFSA Membrane by Molecular Dynamics Simulation International-presentation

220th Electrochemical Society Meeting　2011/10
Development of the new model for the proton hopping by molecular dynamics simulation International-presentation

220th Electrochemical Society Meeting　2011/10
Molecular Dynamics Study of Oxygen Permeation in the PFSA Ionomer on Pt Catalyst Surface International-presentation

220th Electrochemical Society Meeting　2011/10
ホッピングを考慮したプロトン拡散現象の分子動力学的研究

第3回マイクロ・ナノ工学シンポジウム　2011/09/27
周囲の水分子の影響を考慮したプロトンホッピング現象の分子動力学的研究

第3回マイクロ・ナノ工学シンポジウム　2011/09/27
低温水素の熱物性評価に関する分子動力学的研究

日本機械学会第3回マイクロ・ナノ工学シンポジウム　2011/09/27
PEFC触媒層のionomer内における酸素拡散に関する分子論的研究

日本機械学会2011年度年次大会　2011/09/13
ホッピングを考慮したプロトン拡散現象の分子動力学的研究

日本機械学会2011年度年次大会　2011/09/13
固体高分子形燃料電池内部の高分子膜内におけるプロトン・水分子輸送特性に関する分子動力学的解析

日本機械学会2011年度年次大会　2011/09/13
先端的中性子小角散乱法による膜電極接合体の微細構造の研究

日本機械学会2011年度年次大会　2011/09/13
ナノ液柱の潤滑現象に関する分子論的解析

日本機械学会2011年度年次大会　2011/09/12
古典的分子シミュレーションを用いた低温水素の熱物性解析

日本機械学会2011年度年次大会　2011/09/12
酸水素混合系に対するcubic 型状態方程式の精度評価

日本機械学会2011年度年次大会　2011/09/12
多孔質体内のナノスケール気体流れに関する数値的研究

日本機械学会2011年度年次大会　2011/09/12
Characteristics of Friction in Nanoscale Liquid Bridge International-presentation

38th Leeds-Lyon Symposium on Tribology　2011/09/07
グラファイト微細孔内における水滴の挙動に関する分子論的研究

第３回マイクロナノ工学シンポジウム　2011/09
Proton Transfer in Polymer Electrolyte Membrane by Molecular Dynamics Method International-presentation

the 2011 Energy Sustainability Conference & Fuel Cell Conference　2011/08/08
An Estimation of Thermodynamic and Transport Properties of Cryogenic Hydrogen using Classical Molecular Simulation International-presentation

ASME-JSME-KSME Joint Fluids Engineering Cenference 2011　2011/07/26
Molecular Dynamics Simulation of Oxygen Permeation through the Ionomer of PEFC Cathode Side Catalyst Layer International-presentation

ASME-JSME-KSME Joint Fluids Engineering Conference 2011　2011/07/26
古典分子動力学法を用いた低温水素の熱輸送物性評価

第48回日本伝熱シンポジウム　2011/06
PEFC触媒層内ionomerにおける酸素分子透過に関する分子論的研究

第48回伝熱シンポジウム　2011/06/01
高分子電解質膜内部のプロトン拡散現象に関する研究

第48回伝熱シンポジウム　2011/06/01
Analysis of Transport Phenomena in Membrane Electrode Assembly of Polymer Electrolyte Fuel Cell by Molecular Simulation International-presentation

5th Korea-Japan Joint Seminar on Heat Transfer　2011/05/27
PEFC内の白金触媒上ionomerにおける酸素透過に関する分子論的研究

第18回燃料電池シンポジウム　2011/05/19
高分子電解質膜内部のプロトン・水分子輸送に関する分子動力学的解析

第１８回燃料電池シンポジウム　2011/05/19
大規模分子動力学シミュレーションによるPEFC内物質輸送現象の解明

第18回燃料電池シンポジウム　2011/05/19
燃料電池内部流れのマルチスケールシミュレーション

FC EXPO 2011　2011/03/04
A PID Control-Based Scheme for Time-Critical Rendering of Particle Systems International-presentation

Pacific Visualization 2011　2011/03/02
古典的分子シミュレーション手法を用いた低温水素の熱物性評価の限界

日本航空宇宙学会北部支部2011年講演会　2011/03
Molecular Dynamics Study of the Property of Proton Transfer in Perfluorosulfonic Acid Membrane International-presentation

The International Chemical Congress of Pacific Basin Societies (Pacifichem2010)　2010/12/19
A Molecular Dynamics Study on the Thermodynamic Properties of Croygenic Hydrogen International-presentation

Tenth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2010/11/02
Assesment of Different Thermostating Techniques in the Simulation of Molecular Lubrication International-presentation

Tenth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2010/11/02
Analysis of Proton Transferring Property including Grotthus Mechanism in Polymer Electrolyte Membrane International-presentation

The Seventh International Conference on Flow Dynamics　2010/11
Molecular dynamics study of oxygen permeation to catalytic metal covered with polyelectrolyte membrane International-presentation

Seventh International Conference on Flow Dynamics　2010/11
Proton transport in hydrogen bond network of confined water International-presentation

Tenth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2010/11
Transport phenomena of water droplet in a slit pore International-presentation

Seventh International Conference on Flow Dynamics　2010/11
Molecular Dynamics Study of Proton Transfer including Grotthus Mechanism in Polymer Electrolyte Membrane International-presentation

218th ECS Meeting　2010/10
PEFCカソード触媒層イオノマーにおける酸素拡散に関する研究

日本機械学会流体工学部門講演会　2010/10
グラファイト細孔内を移動する水の界面張力

日本機械学会流体工学部門講演会　2010/10
高分子電解質膜内におけるプロトンホッピングを伴うプロトン伝導性に関する分子動力学的研究

日本機械学会流体工学部門講演会　2010/10
水分子ネットワーク構造におけるプロトン輸送特性の解明

日本機械学会流体工学部門講演会　2010/10
低温水素の分子シミュレーションに対する古典的手法のアプローチ限界

日本機械学会流体工学部門講演会　2010/10
高分子電解質膜のプロトンホッピングを伴うプロトン伝導性に関する研究

日本流体力学会年会2010　2010/09/09
大規模粒子系可視化における描画速度の安定化

日本機械学会2010年度年次大会　2010/09/06
ナノ液柱の運動量輸送特性に関する分子論的解析

日本機械学会 2010年度年次大会　2010/09
ナノ細孔内における液滴の移送現象

機械学会年次大会　2010/09
低温水素の熱物性に対する分子間ポテンシャルモデルの影響

日本機械学会 2010年度年次大会　2010/09
分子動力学による白金(111)表面上の水素分子の解離吸着確率モデル

(社)日本機械学会 2010年度年次大会　2010/09
分子動力学法を用いた高分子電解質膜内のプロトン輸送特性の解析

日本機械学会 2010年度年次大会　2010/09
The Molecular Simulation of Cryogenic Hydrogen Using Classical Method International-presentation

21st IUPAC International Conference on Chemical Thermodynamics (ICCT2010)　2010/08
A Modeling of Dissociative Adsorption Probability of the H2-Pt(111) System Based on Molecular Dynamics International-presentation

27th International Symposium on Rarefied Gas Dynamics　2010/07
Dissociation Probality of Gas Molecule on Metal Surface Including Dynamic Effects International-presentation

13th International Conference on Theoretical Aspects of Catalysis　2010/06/23
Molecular dynamics study of transport phenomena of water droplet in a nano slit pore International-presentation

13th International Conference on Theoretical Aspects of Catalysis　2010/06/23
Proton Transfer Including Grotthus Mechanism in Polyelectrolyte Membrane by Molecular Dynamics Simulation International-presentation

13th International Conference on Theoretical Aspects of Catalysis　2010/06/22
燃料電池内部のナノスケール流動現象に対する大規模分子シミュレーション

大阪大学基礎工学研究科特別講義　2010/06/16
高分子電解質膜内におけるプロトンホッピングを伴うプロトン輸送に関する分子動力学的研究

第17回燃料電池シンポジウム　2010/05
高分子電解質膜内におけるプロトン輸送特性の解析

第47回日本伝熱シンポジウム　2010/05
Molecular Dynamics Study of Proton Transport in Polymer Electrolyte Membrane International-presentation

Joint International Symposium on 3rd Micro & Nano Technology and Micro/Nanoscale Energy Conversion & Transport-2010　2010/03/22
非経験的ポテンシャルによる低温水素の熱物性評価

日本航空宇宙学会北部支部2010年講演会　2010/03/10
燃料電池内部における気液流動特性のマルチスケールシミュレーション

FC EXPO 2010　2010/03/04
Nano-Scale Modeling of Confined Liquid Films and Bridges International-presentation

ELyT-Lab Workshop　2010/03
高分子電解質膜におけるプロトン輸送現象の分子論的解析

平成20年度研究所連携プロジェクト成果報告会　2010/02/08
Reliability of Classical Molecular Dynamics Method to Thermodynamic Properties of Hydrogen International-presentation

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition　2010/01
Proton Transfer in Polyelectrolyte Membrane by Molecular Dynamics Simulation International-presentation

ASME 2009 Micro/Nanoscale Heat and Mass Transfer (MNHMT) International Conference　2009/12/20
The Dependence of Motion of Atoms on Dissociation Probability of Gas Molecule International-presentation

ASME 2009 Micro/Nanoscale Heat and Mass Transfer (MNHMT) International Conference　2009/12/20
PEFC用パーフルオロスルホン酸系化合物の劣化機構に関する理論的解析

第50回電池討論会　2009/11/30
MEAの劣化機構に関する理論的解析

日本コンピュータ化学会2009年秋季年会　2009/11/12
A Molecular Study on the Thermodynamic and Transport Properties of Liquid Hydrogen International-presentation

Ninth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2009/11/05
Molecular Dynamics Study about Lubrication Phenomena of Liquid Bridges International-presentation

Ninth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2009/11/05
Molecular Simulation of Nanoscale Flow in Polymer Electrolyte Fuel Cell

the Sixth International Conference on Flow Dynamics　2009/11/05
高分子電解質膜のプロトン輸送特性

第30回熱物性シンポジウム　2009/10/28
A DFT study for the Durability of Perfluorosulfonic Acid Membrane International-presentation

216th Meeting of ElectroChemical Society　2009/10/06
Molecular Dynamics Study of the Dissociation of H2/D2 on Pt(111) Including Thermal Motion Compared with Molecular Beam Experiments International-presentation

216th Meeting of ElectroChemical Society　2009/10/06
燃料電池内部のナノスケール熱・物質輸送現象

2009年度伝熱学会東北支部秋期伝熱セミナー　2009/10/03
A Molecular Dyanmics Study for the Dissociation Phenomena of Gas Molecule on Metal Surface International-presentation

10th International Conference on Atomically Controlled Surface, Interfaces and Nanostructures　2009/09/22
固体高分子形燃料電池MEAの劣化機構に関する理論的解析

第3回分子科学討論会2009　2009/09/21
高分子電解質膜内部のプロトン輸送に関する分子動力学的研究

日本機械学会 2009年度年次大会　2009/09/14
大規模粒子系可視化における時間重視レンダリングの実現

日本機械学会2009年度年次大会　2009/09/14
低温水素の熱物性と分子間ポテンシャルの相関に関する研究

日本機械学会 2009年度年次大会　2009/09/14
分子動力学法による白金表面上の水素解離現象

日本機械学会 2009年度年次大会　2009/09/14
Lubrication Phenomena of Nanoscale Liquid Bridges by Molecular Dynamics Method International-presentation

World Tribology Congress 2009　2009/09/10
The Effect of Different Thermostating Techniques on Friction and Dissipation in Molecular Dynamics Simulations of Confined Lubrication Films International-presentation

World Tribology Congress 2009　2009/09/10
白金表面上の水素分子解離現象に関する分子論的解析

第46回日本伝熱シンポジウム　2009/06
分子動力学法による流体の輸送物性の解析

JAXA社会連携講座第5回研究会　2009/05/26
MEA劣化に関する理論的解析

日本コンピュータ化学会2009年春季年会　2009/05/21
高分子電解質膜内部のプロトン輸送に関する分子動力学的研究

第16回燃料電池シンポジウム　2009/05/12
白金表面での水素分子解離確率に関する分子動力学的解析

第16回燃料電池シンポジウム　2009/05/12
燃料電池内部で生じる反応流動現象のマルチスケール解析

第6回「大気圧プラズマ流による人間環境保全技術に関する講演会」　2009/03/13
パーフルオロスルホン酸系高分子の耐劣化性に関する量子論的解析

電気化学会第76回大会　2009/03
古典分子動力学法による水素の熱力学的性質の再現性の検討

日本航空宇宙学会北部支部2009年講演会　2009/03
A Modeling of Thermal Properties of Hydrogen/Oxygen System Using Molecular Simulations International-presentation

47th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition　2009/01
燃料電池内部のナノスケール熱流動現象の数値解析

大阪大学大学院基礎工学研究科機能創成セミナー・未来ラボ研究会「量子・分子流動ダイナミクスの数理と応用」　2008/12/18
Molecular Dynamics study on dissociation probability of H2 on Pt(111) surface International-presentation

AFI/TFI-2008　2008/12
Continuum/non continuum modeling of thin lubricated films International-presentation

LIA Joint Seminar　2008/12/01
Molecular study about dissociation phenomena of H2 on Pt surface International-presentation

Fifth International Conference on Flow Dyanmics　2008/11
multiscale Analysis of Nanoscale Flow Phenomena Including Chemical Reactions International-presentation

東北大学流体科学研究所ー清華大学航天航空学院ジョイントワークショップ　2008/10/28
白金表面における水素分子の解離確率に関する分子動力学的研究

日本機械学会 2008年度年次大会　2008/08
Nano-Scale Modeling of Tribological Interfaces International-presentation

ELyT and ”Core to core” Seminar　2008/06/23
PEFC高分子電解質膜側鎖の対劣化性能に関する量子・分子論的解析

第75会電気化学会大会　2008/03
不規則性多孔質電極構造最適化に向けた三次元多孔質シミュレータの応用

第75会電気化学会大会　2008/03
Proton Transfer in Polyelectrolyte Membrane by Molecular Dynamics Simulation

Satoshi Ito, Takashi Tokumasu

The Seventh International Symposium on Advanced Fluid Information and the Fource International Symposium on Transdisciplinary Fluid Integration　2007/12
Numerical Analysis for the Characteristics of Heat and Fluid Flow Against the Pattern of Channel in PEFC International-presentation

Kohji Imuta, Takashi Tokumasu

Seventh International Symposium on Advanced Fluid Information and the Fource International Symposium on Transdisciplinary Fluid Integration　2007/12
Molecular Dynamics Study About Dissociation Phenomena of H2 on Pt(111) Surface International-presentation

Daigo Ito, Takashi Tokumasu

The Seventh International Symposium on Advanced Fluid Information and the Fource International Symposium on Transdisciplinary Fluid Integration　2007/12
DFT study of the degradation of Nafion and its substitutional compound International-presentation

Takashi Tokumasu, Izumi Ogawa, Kiyoe Funamoto, Michihisa Koyama, Akira Miyamoto

International Symposium on High-Tech Batteries　2007/11
Study on dissociation probability of H2 on Pt(111) surface International-presentation

Daigo Ito, Takashi Tokumasu

Fourth International Conference on Flow Dynamics　2007/09
Effect of Motion of Molecule on the Dissociative Adsorption Phenomena International-presentation

Takashi Tokumasu, Daigo Ito

Fourth International Conference on Flow Dynamics　2007/09
The Dependence of Molecular Motion on the Dissociative Adsorption of H2 on Pt(111) International-presentation

Takashi Tokumasu, Daigo Ito

2007 ASME-JSME Thermal Engineering Summer Heat Transfer Conference　2007/07
THE EFFECT OF THE MOTION OF SURFACE ATOMS ON THE DISSOCIATIVE ADSORPTION OF HYDROGEN MOLECULE International-presentation

Takashi Tokumasu

Japan NANO 2007　2007/02/20
Molecular Dynamics Study for the Gas Molecule Adsorbed on Metal Surface International-presentation

International Forum for Joint Anniversary　2007/02
Dissociation Phenomena of H2 on Pt(111) Surface International-presentation

Takashi Tokumasu

the Third International Conference on Flow Dynamics　2006/11/07
超微小界面の反応流動機構

徳増崇

第10回オーガナイズド混相流フォーラムOMF2006　2006/10/16
白金表面における水素分子の解離吸着

徳増崇, 大平勝秀

日本流体力学会年会2006　2006/09/15
the European Conference of Surface Science International-presentation

Takashi Tokumasu, Kanako Hara, Katsuhide Ohira

the European Conference of Surface Science　2006/09/04
Dissociation Probability of H2 on Pt Surface International-presentation

Takashi Tokumasu, Kanako Hara, Katsuhide Ohira

the Third International Symposium on Transdisciplinary Fluid Integration　2006/06/12
白金表面における水素分子解離吸着現象に関する分子動力学的解析

徳増崇, 原香菜子, 大平勝秀

第13回燃料電池シンポジウム　2006/05/16
Dissociative Adsorption of H2 on the Electrode Catalyst of Fuel Cell International-presentation

Takashi Tokumasu, Kanako Hara, Katsuhide Ohira

Japan NANO 2006　2006/02/20
キャビテーションの熱力学的効果に対するレイノルズ数の影響

徳増崇, 関野夕美子, 上條謙二郎

第55回理論応用力学講演会　2006/01/24
The Effect of Rotational Degree of Freedom on Bubble Nucleation in Liquid Oxygen International-presentation

2nd International Conference on Flow Dynamics　2005/11
Molecular Dynamics Study of the Dissociative Adsorption of H2 on Pt(111) International-presentation

Nanoscale Transport Phenomena - Science and Engineering　2005/07
Quantum Molecular Dynamics Simulation of Dissociative Adsorption of H2/Pt(111) International-presentation

24th International Symposium on Rarefied Gas Dynamics　2004/07
A New Modeling of Sheet Cavitation Considering the Thermodynamic Effects

CAV2003　2003/11
A Numerical Study of Thermodynamic Effects of Sheet Cavitation International-presentation

2002 ASME Fluid Engineering Division Summer Meeting　2002/07
Dynamic Molecular Collision (DMC) Model for General Diatomic Rarefied Gas Flows International-presentation

23rd International Symposium on Rarefied Gas Dynamics　2002/07
The Thermodynamic Effects of Cavitation Around a 2-D Hydrofoil International-presentation

Advanced Fluid Information 2001　2001/10
Molecular Dynamics Study of the Nucleation of Bubble International-presentation

CAV2001　2001/06
Dynamic Molecular Collision Model for N${}_$-He Mixture International-presentation

22nd International Symposium on Rarefied Gas Dynamics　2000/07
Bubble Nucleation in Liquid Oxygen International-presentation

2000 ASME Fluid Engineering Division Summer Meeting　2000/06
The Structure of Free Jet Expansion of Binary Gas Mixture International-presentation

Molecular and Microscale Thermophysical Phenomena in Nanotechnology　1999/08
Dynamic Molecular Collision (DMC) Model of Diatomic Molecules for DSMC Calculation International-presentation

21st International Symposium on Rarefied Gas Dynamics　1998/07
The Construction of Collision Model of Diatomic Molecules International-presentation

Colloquium on Nonequilibrium Phenomena of Low-Density Jets in Space　1998/02
The Numerical Simulations of Diatomic Rarefied Gas Flows International-presentation

International Conference on Fluid Engineering　1997/07

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Research Projects 26

Development of Nanochannel Membranes Having Rapid Transport Properties in Aqueous and Non-aqueous Solutions

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Challenging Research (Pioneering)

Institution: Tokyo Institute of Technology

2023/06/30 - 2026/03/31
Construction of thin film deposition model in CVD / ALD method considering chemical reaction and interfacial flow phenomenon

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2021/04/01 - 2024/03/31
Analysis of hydrogen transport in a metal by quantum/molecular/statistical dynamics

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Challenging Research (Exploratory)

Institution: Tohoku University

2021/07/09 - 2023/03/31
Analysis of multi-scale mass transport phenomena in catalyst layer for the development of the efficiency of polymer electrolyte fuel cell

Tokumasu Takashi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2018/04/01 - 2021/03/31

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A Catalyst Layer (CL) of polymer electrolyte fuel cell is an important part whose structure determines the performance of the fuel cell, but the detail relationship between nano-mesoscale transport / structural characteristics inside the catalyst layer and the battery performance has not yet been understood. In this study, we first simulate the proton transport characteristics inside the ionomer adsorbed on the carbon surface in the catalyst layer by molecular dynamics simulation, and analyze the dependence on the water content and film thickness. Next, the result is modeled and implemented in the 3D simulator of catalyst layer performance. Using this model, the current-voltage characteristics of the catalyst layer are calculated, and the effects of nanoscale transport characteristics in ionomer and nano-meso structural characteristics of the catalyst layer on fuel cell performance are analyzed.
Investigation of Effects of Coaxial Injector Shape on Mixing, Diffusion, and Combustion Process of Cryogenic High-Pressure Propellant

Tsuboi Nobuyuki, KOSHI Mitsuo, HAYASHI A. Koichi, TOKUMASU Takashi, TSUDA Shinichi, TERASHIMA Hiroshi, SHIMIZU Taro, ASAHARA Makoto, MORII Youhi, NAGASHIMA Hiroki, MUTO Daiki, OZAWA Kohei

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Kyushu Institute of Technology

2015/04/01 - 2018/03/31

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The numerical and experimental studies on the cryogenic flow under the transcritical and supercritical pressures are performed in order to understand the thermodynamic characteristics and fluid dynamics. The coaxial cryogenic nitrogen jet flows under the supercritical pressure are simulated using ILES/RANS hybrid method. The mean inner jet lengths of the present simulations agree well with those of the previous experiments and numerical simulations. As for the multi-species flow simulations, the numerical method using a hybrid method between the energy equation and pressure-evolution-equation, which is able to prevent from pressure oscillations in the flow, is developed. In the experiments, visualization data and temperature profiles in the cryogenic nitrogen channel flow are measured under the subcritical and supercritical pressures.
Theoretical design of high durability polymer elelctrolyte membrane by the flow and structure control based on quantum/molecular simulations

TOKUMASU Takashi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Challenging Exploratory Research

Institution: Tohoku University

2013/04/01 - 2016/03/31

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First we constructed a simulator to analyze the transport phenomena of proton and OH radical in polymer electrolyte membrane with considering the hopping mechanism in the framework of classical molecular dynamics method. Next,we obtained the knowledge about the nanoscale structure of water cluster in polymer electrolyte membrane which has both high proton conductivity and low OH radical conductivity. Consequently, we succeed the modeling of proton hopping which can express the energy barrier of proton hopping obtained by quantum chemical calculations accurately. Using the model, we succeed to make a simulator to analyze the proton transport phenomena. Using the simulator we analyze the dependence of water content on the diffusivity of proton and OH radical. Consequently, it is found out that the diffusivity of proton and OH radical increases with the increase in water content and the diffusivity of proton is larger than that of OH radical.
Construction of molecular dynamics simulator for analyses of flow phenomena of hydrogen by considering quantum effect

TOKUMASU Takashi, TSUBOI Nobuyuki, TSUDA Shin-ichi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2012/04/01 - 2015/03/31

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The effect of quantum effect of hydrogen molecule on the thermal properties and transport phenomena of liquid hydrogen was analyzed. Both the centroid molecular dynamics method and classical molecular dynamics method was used. As for the thermal properties, the difference of its characteristics from principle corresponding state which cannot be explained on the standpoint of classical dynamics was clearly explained by considering the quantum effect of hydrogen molecule. As for the transport phenomena, diffusion coefficient of hydrogen molecule do not change even though the quantum effect was considered. The thermal conductivity of liquid hydrogen by considering the quantum effect become smaller than that by evaluating the standpoint of classical dynamics.
Research of Combustion Dynamics on Cryogenic Flow under Supercritical Pressure

TSUBOI Nobuyuki, TERAMOTO Susum, KOSHI Mitsuo, HAYASHI Hayashi, TOKUMASU Takashi, TSUDA Shinichi, SHIMIZU Kazuya, TERASHIMA Hiroshi, SHIMIZU Taro, TANI Hiroumi, ASAHARA Makoto, MORII Youhi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Kyushu Institute of Technology

2011/04/01 - 2014/03/31

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The numerical and experimental studies on the cryogenic flow under the supercritical pressure are performed in order to understand the thermodynamic characteristics and fluid dynamics. The averaged density distributions of the mono-axial nitrogen jet flow under the supercritical pressure using RANS simulations agree well with the experimental data. The preconditioning method including multi-species mass-conservation equations was developed to capture the unsteady feature near the shear layer in the low-speed H2/O2 shear flow. As for LES simulations, the cryogenic nitrogen/nitrogen mixing layers in ideal-gas and transcritical conditions were also simulated. The results show that the effects of the pseudo-critical temperature are small on the turbulent eddy structure. In the experiment for the cryogenic nitrogen jet under the transcritical pressure, the temperature gradient along the symmetric line becomes small near the pseudo-critical temperature.
Development of polymer electrolyte membrane which is difficult to degrade by controlling the structure of water cluster in the membrane

TOKUMASU Takashi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Challenging Exploratory Research

Institution: Tohoku University

2011 - 2012

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First we constructed a simulator to analyze the transport phenomena of proton and OH radical in polymer electrolyte membrane with considering the hopping mechanism by molecular dynamics method. Using the simulator, we obtained the knowledge about the nanoscale structure of water cluster in polymer electrolyte membrane which has both high proton conductivity and low OH radical conductivity to make the theoretical design of next generation polymer electrolyte membrane. Consequently, we succeed the modeling of proton hopping which can express the energy barrier of proton hopping obtained by quantum chemical calculations accurately. Using the model, we succeed to make a simulator to analyze the proton transport phenomena. Using the simulator we analyze the dependence of water content on the diffusivity of membrane. Consequently, it is found out that the diffusivity of membrane increases with the increase in water content and the diffusivity of water is larger than that of proton.
Theoretical design of polymer electrolyte membrane which has high proton conductivity by quantum-classical molecular dynamics study

TOKUMASU Takashi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Young Scientists (B)

Institution: Tohoku University

2009 - 2010

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On the basis of proton hopping mechanism, we have developed a simulator which enables to analyze proton (H^+) hopping in polymer electrolyte membrane by quantum-classical molecular dynamics study. With this simulator, we have conducted the study to comprehend the nanoscopic proton transfer mechanism in polymer electrolyte membrane. As a result, we succeeded in creating a model of proton hopping that accurately represents energy barrier calculated by quantum chemical calculation. And also we succeeded in structuring proton transfer simulator with the model embedded in it. By computing diffusion coefficient using the simulator varying water content, it was found that diffusion coefficient increases with increased water content and that the diffusion coefficient of water is faster than the diffusion coefficient of proton.
Investigation of the mechanism of nano-scale gas lubrication via molecular gas dynamics approach

YONEMURA Shigeru, TOKUMASU Takashi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2008 - 2010

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In this research, we paid attention to the low friction which appeared when the sliding speed of diamond coating on a rotating metal disk was increased to 2-3 m/s. We solved the lubrication mechanism of this low friction by way of numerical simulation and showed that the diamond coating was floated by high pressure induced by micro/nano-scale gas flow between the diamond coating with micro/nano-scale surface structure and the counter metal surface. We also showed that this was a new phenomenon peculiar to micro/nano-scale gas flow.
Development of Mezzo-Scale Thermo-Physical Model and Chemical Reaction Model for Supercritical Combustion Flow

TSUBOI Nobuyuki, KOSHI Mitsuo, HAYASHI A.koichi, SHIMIZU Taro, SHIMIZU Kazuya, TSUDA Shinichi, YAMADA Eisuke, TOKUMASU Takashi, MATSUMOTO Yoichiro, TAKAGI Shu, YAMANISHI Nobuhiro

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Japan Aerospace Exploration Agency

2007 - 2009

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The multi-scale method for the hydrogen/oxygen supercritical combustion flow under high pressure is applied to understand the thermo-physical phenomena. The present study is focused on (1) the construction of thermo-physical properties and equation of state, (2) the modification of the chemical reaction model, and (3) the improvement of the compressible Navier-Stokes solver by using the preconditioning method. For the first task, the temperature and density saturation curve for the molecular dynamics simulations were compared with those for NIST data to show the agreement under the small rotational quantum effects. For the second task, the chemical reaction model was improved to show that the ignition delay times and the laminar flame velocities for the present model agreed well with the experimental data. For the third task, the compressible flow solver with the preconditioning method showed the ability to solve such the low speed flow around a cylinder and an aerofoil.
Optimum Control of Plasma Flow Systems through Multi-Scale Integration

NISHIYAMA Hideya, HAYASE Toshiyuki, SATO Takehiko, TOKUMASU Takashi, TAKANA Hidemasa

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (A)

Institution: Tohoku University

2005 - 2007

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In the present study, the plasma flow systems with multi-scale interactions are analyzed by using multi-scale control method and multi-scale integration to give the fundamental data for cold spray, plasma assist combustion, arc melting process and gas circuit breaker. The obtained results are as follows. 1. An integrated model for advanced cold spray process is constructed by integrating nano-micro particle flow model and coating formation model. It is clarified that electrostatic acceleration of nano-particle is effective in the presence of shock wave. The deposition process in the cavity is also clarified by comparing with cold spray experiment. 2. The pulsed arc torch and dielectric barrier discharge torch with small input power are developed to produce oxygen and nitrogen radicals and ozone for combustion assist. The effects of applied voltage and frequency on radical concentrations are clarified experimentally. Time evolution of chemical species in an air plasma are also clarified numerically using complex reaction model 3. Real time simulations are conducted for purpose of compactness of gas circuit breaker (GCB) and optimization of arc melting process. It is clarified that rough structure in the exhaust tube enhances the rapid cooling of exhaust hot gas for compact GCB. It is shown that the temperature dependent surface tension and mushy zone effect the melting pool structure in an arc-melting systems.
PEFC電極触媒表面での解離吸着現象に関する量子・分子動力学的解析

徳増崇

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(B)

Institution: 東北大学

2005 - 2006

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近年の地球温暖化問題への対策から、次世代電源として燃料電池への期待が高まっている。とくに固体高分子形燃料電池(PEFC)はその起動の早さ、動作温度の低さから現在最も注目されている。このPEFCでは電極触媒として白金(Pt)を使用しているが、この白金は高価である上に空気極においては高活性ではなく,さらに燃料極においても被毒などの問題を生じるため、燃料電池の高効率化、低コスト化を実現するためにはこのPt表面上での触媒反応のメカニズムを詳細に解析する必要がある。上記の理由により,本研究では触媒としてPtを取り上げ,また燃料電池の触媒反応の中で最も簡単な反応であるH_2の解離吸着現象に注目して解析を行った.計算手法としては,Embedded Atom Method (EAM)を使ったMolecular Dynamics (MD)法を用い,Pt表面上におけるH2の解離吸着現象を解析した.今年度は前年度に構築したシミュレーション手法を用いて様々な条件下における水素の解離確率の計算を行った。その結果、まず表面を構成するPt原子が固定されている系に比べて、T=300[K]程度の熱運動をしている系のほうが解離確率の入射エネルギー依存性に広がりがあることが明らかとなった。またこの原因を詳細に調べた結果、Pt原子が熱運動をすることによって表面のポテンシャルエネルギー面(PES)が劇的に変化し、そのため解離障壁が著しく変化することが原因であることを突き止めた。さらに入射分子の回転状態を変化させて解離確率を計算したところ、入射エネルギーが低い状態では回転エネルギーの低い状態のときには回転エネルギーの増加につれて解離確率が一旦減少し、その後増加に転じることが明らかとなった。これは回転エネルギーが増加するにつれて分子が表面からの束縛を受けにくい状態となり、そのためより低い解離障壁をとる配向になりにくいためであることがわかった。
Study on Instability of Subcooled Cryogenic Cavitating Flows

OIKE Mamoru, TOKUMASU Takashi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Ishinomaki Senshu University

2004 - 2005

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In this study, the experimental research was carried out about the cavitating flow of liquid nitrogen both at normal boiling point (NBP) and subcooled densified condition, and some knowledge about subcooled cryogenic fluid has been obtained. The experiments were performed at cryogenic two phase flow test equipment. A cylindrical converging-diverging nozzle is installed in the test section, which has 2.2mm throat diameter and a 1.21/25 contraction area ratio. During the experiment, pressures and temperatures at both upstream and downstream of the throat were measured, as well as volume flow rate and kinetic pressure. In the case of subcooled condition, from the results of experimental measurements and observations, the fluid of higher flow rate was allowed to be passed through the throat without cavitation, compared with NBP conditions. The flow rate of subcooled condition at 68K reaches three times as much as that of NBP condition. Also, the different types of cavitating flow were observed in subcooled conditions. The cavitation occurrence was intermittently, that is, cavitating flow could not stay long time period and it shifted back to the single phase liquid flow. This is explained by choked flow at the throat caused by reduced acoustic velocity. This intermittent occurrence of cavitation was not only interesting phenomena, but also important in engineering application. While the cavitation occurred intermittently, the large amplitude of oscillations was induced at the same time. The pressure fluctuation amplitude reaches a maximum 35% of the base pressure, and seems to be a dangerous phenomenon in engineering applications. These phenomena about subcooled cavitating flow are governed by acoustic velocity and cavitation number which change with temperature conditions. In this research, the relationship between the flow appearance and cavitation number or acoustic velocity was shown for predicting the cavitating flow phenomena of subcooled cryogenic fluids.
広い範囲の速度,ボイド率を有する気液二相流解析のための数値解法の開発

申炳録, 徳増崇, 山本悟

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(C)

Institution: 東北大学

2003 - 2005

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本研究は、キャビテーションまたは非平衡凝縮を伴う気液二相流れに対して、非圧縮性の支配的な低マッハ数(一様マッハ数0.001以下)流れから圧縮性の超音速流れまでの、広い範囲(0から1まで)のボイド率(液体における気相の体積分率)が混在する流れが解析できる数値解法の開発を目的として行われた。本年度はまず気液二相流れの数理モデルとして、筆者らにより提案した局所均質媒体モデルを用い、熱力学的関係に基づく相変化モデルを加えた。また、圧縮性/非圧縮性混在の流れを精度を良く解析するため、密度をベースとする基礎方程式にPreconditioningを施した新たな数値解法を提案した。本研究成果は、いくつかの国際会議と雑誌で発表された。
ナノバブル混入液体のミクロ・マクロ特性に関する分子動力学的解析

徳増崇

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(B)

Institution: 東北大学

2003 - 2004

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液体中に気泡(ナノバブル)を安定して存在させ、その気泡混入状態の液体のミクロ、マクロ特性を分子動力学法により解析した。平成15年度は分子動力学法により気泡が安定して存在する計算系の設定を行った。その結果、液体中の温度を制御して熱伝導率を計算する手法では温度制御領域に気泡ができてしまい、正しく計算が行われないことが明らかとなった。この結果を踏まえて平成16年度は液体の両端に固体壁を設け、固体壁の温度を制御する事で熱伝導率の計算を行うようにした。またこのようにして得られた値とGreen-Kuboの公式などで得られた値との比較を行った。また液体中の密度揺らぎを定量化して熱伝導率との因果関係を求める解析も行った。密度揺らぎはある条件下における単相液体状態の分子動力学計算を行い,その計算領域をいくつかの小さなセルに分割してそのセルがある密度を取る確率分布を求め,その代表値を密度揺らぎを表す指標として用いた。しかしながらこの解析の結果、ナノバブル混入液体中の密度揺らぎと熱伝導率との間には特に定量的な知見は得られなかった。また液体を二原子分子として取り扱った系の計算を同様にして行い,液体分子が内部自由度を持つことによって核生成速度にどのような影響が生じるかを解析した。液体分子は2Center Lennard-Jonesポテンシャルを仮定した。その結果、ナノバブル混入液体中の気液界面にはあまり温度ジャンプがみられなかったが、気相がナノバブルとしてではなく完全に流路を横切るようにして存在する径では気液界面に大きな温度ジャンプが存在することが明らかとなった。
燃料電池内部の反応流に関する研究 Competitive

System: Basic Science Research Program

2003/04 -
Study on Instabilities of Two-Phase He II/vapor flow in a pipe

KAMIJO Kenjiro, MATSUMOTO Yoichiro, TOKUMASU Takashi, OIKE Mamoru, YAMADA Hitoshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2001 - 2003

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The aim of this research is to investigate the instability of supersaturated cryogenic two-phase flow experimentally and theoretically. This analysis is useful to the improvement of cryogenic apparatus such as turbopumps of rocket engine. In this year numerical simulations are performed about the two-phase flow in the nozzle. The drift-flux model is used as the cavitation model and axisymmetric system is also used. The phase change is considered. As the results, the effect of phase change on flow field of cryogenic fluid appears the suppression of the increase of void fraction at the center of wake vortex generated downstream of nozzle throat. Moreover, it is confirmed that the counter flow generates at the wall of the nozzle as the wake vortex downstream of the nozzle throat grows up. Next, experiments are performed about the visualization of two-phase flow of supersaturated cryogenic fluid. The data of both instability flow and stability one are obtained. As the results, the cavitating flow at saturated state is comparatively stable and the successive generation of bubble is observed. On the contrary, the cavitating flow at supersaturated state is very unstable and arbitrary generation of bubble is observed.
Study on Instabilities of Two-Phase He II/vapor flow in a pipe

KAMIJO Kenjiro, MATSUMOTO Yoichiro, TOKUMASU Takashi, OIKE Mamoru

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2000 - 2002

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The aim of this research is to analyze the flow instability of multi-phase flow of liquid helium which consists of superfluid, normalfluid and vapor phase. The experimental apparatus for the generation of multiphase flow of superfluid helium is improved. It is important to shield the superfliud helium from the heat for high accuracy measurement. To protect the liquid helium from the outside heat the copper shield is added to the upstream and downstream tank and around the test section. Using this improved apparatus, the two-phase flow of superfluid helium is generated at the test section and the data of the relation between Reynolds number and cavitation number are obtained. For this reason, it is confirmed that the cavitation number is decreased as the Reynolds number is increased. Moreover, the phenomena are analyzed by the numerical method. The two-phase flow is assumed as bubble cavitation and the governing equations are constructed so that continuum equation, momentum equation and energy conservation is satisfied. These equations are solved by SMAC method and the flow structure at the nozzle is analyzed. Consequently, at the blowdown, the pressure decreases immediately and vortex is generated downstream of the throat.
極低温流体中の気泡生成に関する研究

徳増崇

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 奨励研究(A)

Institution: 東北大学

2000 - 2001

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1.分子内自由度の熱伝導率に与える影響本研究では分子種いろいろ変化させて熱伝導率の計算を行い、分子内自由度が熱伝導率に与える影響について解析を行った。その結果、対臨界値が同じになる条件で計算した熱伝導率はLennard-Jonesポテンシャルのパラメータで無次元化した分子径の大きさに強く依存しており、その値が増すほど熱伝導率の値も増加する傾向があることが明らかとなった。またその内訳を見ると、液体中の熱伝導(エネルギの輸送)は分子衝突によるものが支配的であること、対臨界値が同じ条件の系の場合、衝突による並進エネルギの輸送はほぼ一定であるが、回転エネルギの輸送は大きく変化することが明らかとなった。これは対応状態原理によりこれらの計算条件では圧力の対臨界値が一致しており、熱伝導率の並進の衝突項と圧力は強い相関を持つが、回転の衝突項は圧力にはほぼ無関係に決定されることが原因であることが明らかとなった。 2.気泡生成時の液体中の非平衡状態の分子動力学的解析本研究では気泡生成時に発生する非平衡状態がどのように緩和するかを分子動力学法により解析した。その結果、ポテンシャルエネルギが比較的高い状態にあった液体がそのポテンシャルエネルギを解放して飽和状態になり、その解放されたエネルギが液体の流速と温度に変換される様子が観察された。またこの圧力波の波面厚さや伝播速度なども計算することができた。しかしこの変化は密度が2.6%、温度が10%程度の変化であり、期待していたような各自由度間の明確な温度非平衡は観察されなかった。また温度や密度などの物理量が変化しているところでの状態はその液体の状態方程式で与えられる値と良く一致し、この現象には液体分子が内部自由度を持つことによる非平衡性はあまり影響しないことが明らかとなった。
STUDY ON SYSTEM PERFORMANCE OF LIQUIEFIED AIR CYCLE ENGINE

KAMIJO Kenjiro, TUJIMOTO Yoshinobu, TOKUMASU Takashi, OIKE Mamoru, YAMADA Hitoshi, TAMURA Hiroshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: TOHOKU UNIVERSITY

1999 - 2001

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Based on the experimental results, an analytical method of estimating a liquefaction (mass of liquefied air cooled by 1 kg of liquid hydrogen), and an outlet temperature of liquid hydrogen of the heat exchanger was established, by which we easily evaluate the performance of the heat exchanger cooled by liquid hydrogen. Using this analytical method, we will be able to easily improve the performance of heat exchanger. The specific impulse of LACE was estimated using the above -mentioned method. More than 1,000 second of the specific impulse was calculated even in a simple LACE system. The higher specific impulse will be able to obtain by improvement of the heat exchanger, selection of the optimum LACE system, the selection of the optimum delivery pressure of liquid hydrogen pump, etc. Judging from the mentioned above performance of the present LACE engine, it will be considered that the LACE engine would be a one of the candidates of a rocket based combined cycle engine for a future reusable launch vehicle. The effect of the flight trajectory on the LACE engine was numerically investigated. The numerical results showed that the specific impulse of the present LACE system was smaller than that expected in the low flight Mach number. Therefore, some means, for instance the use of subcooled liquid hydrogen, will be required which enhance the performance of the LACE engine in the low flight Mach number.
Study on Two Phase Flow in Cryogenic Fluids Competitive

1999/04 -
Study on Bubble formation in Liquid Oxygen Competitive

1999/04 -
Study on Instabilities of Cryogenic Two-Phase Flows in a Pipe

OIKE Mamoru, TUJIMOTO Yoshinobu, MATSUMOTO Yoichiro, KAMIJO Kenjiro, TOKUMASU Takashi, ISHIMOTO Jun

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: TOHOKU UNIVERSITY

1998 - 1999

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Applications using cryogenic fluid generally encounter obstacles or complex pipe shapes such as an orifice or a converging-diverging nozzle. Therefore, a flow visualization study on boiling two-phase flow of liquid helium passing through the convergent-divergent nozzle of a horizontal pipe was carried out. The pipe is filled with pressurized liquid helium and flow immediately occurs by opening the on-off valve installed in the pipe outlet. Liquid helium is continuously supplied form the storage tank, the flow is accelerated at the nozzle throat and the phase change is induced by a pressure decrease. The transient evolution of the multi-bubble dispersion was observed from a high-speed video image. Comparison with results of liquid helium and liquid nitrogen indicated that the two-phase flow state of liquid helium is much more rapidly formed in a more homogeneous bubbly mixture two-phase flow than that of liquid nitrogen. The fundamental feature of two-phase flows is its multi-scale structure. Thus, numerical analyses were carried out in the following scales : The bubble formation in liquid oxygen was simulated by the Molecular Dynamics method. Lennard-Jones potential is used as the intermolecular potential. Simulations were carried out at various number densities in order to determine the number density at the limit of metastability. The results showed that in the liquid of diatomic molecules the bubble is formed at large number density than in the liquid of monatomic molecules against the prediction of the equation of sate of Lennard-Jones fluid. The direct numerical simulations of rising spherical bubbles in an impure liquid were conducted for various gravities and void fractions. The Navier-Stokes equations were solved by the finite difference method with the rectangular grid system. The mean velocity field induced by rising bubbles was investigated for various void fractions. The results showed that the boundary thickness becomes thinner in the higher void fraction due to the stronger bubble-bubble interaction. The two-dimensional characteristics of the oiling two-phase flow of liquid helium in a duct were numerically investigated. The governing equations based on the unsteady drift-flux model were conducted and several flow characteristics were numerically calculated, taking into account the effect of superfluidity. The results showed that the vapor gas phase rapidly spreads throughout the inner flow duct because of the change of the pressure gradient due to the effect of superfluidity which appears in momentum equations.
Study on Collision Model of Diatomic Molecules in DSMC method Competitive

1993/04 -

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Social Activities 3

出前講座「IVICTユニバーサイエンス」

2011/12/12 -

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仙台青陵中等教育学校で3,4年生を対称に流体力学の講義を行った。
みやぎ県民大学大学開放講座

2011/09/30 -

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一般の人を対象に、「ミクロのながれ」について講義を行った。
出前講座「IVICTユニバーサイエンス」

2010/08/29 -

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新潟県立柏崎翔洋中等教育学校で高校1,2年生を対称に流体力学の講義を行った。

Other 6

高分子電解質膜内部の水クラスター構造の解明

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高分子電解質膜内部の水クラスターの構造を中性子小角散乱実験および分子動力学法による数値計算により明らかにする。
アニオン界面活性剤の挙動に関する分子論的研究

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アニオン界面活性剤の挙動について、分子論的に解析を行う。
水分子ネットワーク構造におけるプロトン輸送特性の解明

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固体表面近傍におけるプロトン輸送現象を分子動力学法により解析し、そのメカニズムを把握する。
Molecular Dynamics study about the nanoscale lubrication phenomena of liquid bridge

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ナノスケールの液中存在下での摩擦現象を分子動力学法を用いて解析した。液中は水とし、壁面は疎水面としてSiを、親水面としてSiO2を用いた。この系において壁面を一定速度で動かし、液中の幅や高さに対するせん断力の強さについて解析を行った。
液体水素の熱物性に関する分子論的解析

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液体水素の熱物性を分子動力学法により解析し、その量子効果発現メカニズムを解明する。
省スペース型水素貯蔵マグネシウム合金の開発

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二輪車に搭載可能な省スペース型の水素吸蔵合金を開発する。

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