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Yuji Hattori

Section

Institute of Fluid Science

Job title

Professor

Degree

Doctor of Science (The University of Tokyo)

researchmap

https://researchmap.jp/read0145778

J-GLOBAL ID

200901026997412505

Research History 6

2000/04 - 2009/03

Faculty of Engineering, Kyushu Institute of Technology　Associate Professor
2001/10 - 2002/10

Department of Applied Mechanics and Theoretical Physics　客員研究員
1998/10 - 2000/03

Faculty of Engineering, Kyushu Institute of Technology　講師
1994/05 - 1998/09

Institute of Fluid Science, Tohoku University　助手
2009/04 -

Institute of Fluid Science, Tohoku University　Professor
1994/04 -

Institute of Industrial Science, University of Tokyo　研究員（学振）

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Education 2

The University of Tokyo　Graduate School, Division of Science　Department of Physics

- 1994/03
The University of Tokyo　Faculty of Science　Department of Physics

- 1989/03

Committee Memberships 15

科学技術振興機構　さきがけ研究領域「複雑な流動・輸送現象の解明・予測・制御に向けた新しい流体科学」領域アドバイザー

2021/04 - Present
日本流体力学会　フェロー会員

2016/02 - Present
日本流体力学会　フェロー会員

2016/02 - Present
日本機械学会　校閲委員

2009/04 - Present
日本機械学会　校閲委員

2009/04 - Present
日本物理学会　領域11副代表

2021/04 - 2022/03
Japan Society of Fluid Mechanics　Director

2020/02 - 2022/02
日本機械学会東北支部　商議員

2015/03 - 2017/02
日本機械学会東北支部　商議員

2015/03 - 2017/02
日本機械学会　代議員（東北支部, 流体工学部門）

2013/04 - 2015/03
日本機械学会　代議員（東北支部, 流体工学部門）

2013/04 - 2015/03
日本流体力学会　理事

2013/02 - 2015/02
日本流体力学会　理事

2013/02 - 2015/02
日本機械学会東北支部　代議員

2011/04 - 2013/03
日本機械学会東北支部　代議員

2011/04 - 2013/03

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Professional Memberships 4

American Physical Society
The Japan Society of Mechanical Engineers
The Japan Society of Fluid Mechanics
Physical Society of Japan

Research Interests 16

数値流体力学
電磁流体
MHD(magnetohydrodynamcis)
hydrodynamic stability
mathematical physics of fluid dynamics
安定性
rotating turbulence
sound-flame interaction
CFD(Computational Fluid Dynamics)
vortex dynamics
回転乱流
音波と火炎の相互作用
渦運動
aeroacoustics
空力音
流体数理

Research Areas 3

Informatics / Computational science /
Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Fluid engineering /
Natural sciences / Mathematical physics and basic theory /

Awards 1

日本流体力学会竜門賞

2006/02　日本流体力学会

Papers 188

Mechanism of Ranque–Hilsch effect at low Reynolds numbers Peer-reviewed

Taihei Yamamoto, Yuji Hattori

International Journal of Heat and Mass Transfer　252　127382-127382　2025/12
Publisher: Elsevier BV
DOI： 10.1016/j.ijheatmasstransfer.2025.127382 　

ISSN： 0017-9310
Triangular instability of a strained Lamb–Oseen vortex Peer-reviewed

Aditya Sai Pranith Ayapilla, Yuji Hattori, Stéphane Le Dizès

Journal of Fluid Mechanics　1016　2025/07/29
Publisher: Cambridge University Press (CUP)
DOI： 10.1017/jfm.2025.10409 　

ISSN： 0022-1120

eISSN： 1469-7645

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In this study, we demonstrate, for the first time, the existence of a short-wave instability in a Lamb–Oseen vortex subjected to a triangular strain field generated by three satellite vortices, which we term the triangular instability. We identify this instability by numerically integrating the linearised Navier–Stokes equations around a quasi-steady base flow to capture the most unstable mode and validate it by comparing results with theoretical predictions. We evaluate this instability by calculating the growth rates associated with the parametric resonant coupling of two Kelvin waves with the triangular strain field in the limit of small strain rate and large Reynolds number. Our analysis reveals that resonance occurs only for combinations of the azimuthal wavenumbers $m = 1$ and $m = - 2$ (or their symmetric counterparts with opposite signs). We observe several unstable modes with positive growth rates for a moderate viscous Reynolds number $10^4$ and straining parameter value $\epsilon = 0.008$ , defined as the cube of the ratio of the core size to the distance from the satellite vortices. The most unstable mode, dominant at typically high Reynolds numbers, has $k \approx 5.18/a$ and $\omega \approx - 0.312\Omega$ (where $a$ and $\Omega$ denote the core size and central angular velocity). It exhibits negligible critical layer damping and remains the most unstable mode over a wide range of ${Re}$ and $\epsilon$ . At lower Reynolds numbers, another mode with $k \approx 1.76/a$ and $\omega \approx - 0.407\Omega$ , despite significant critical layer damping, becomes the most unstable.
Stability of Stuart vortices in rotating stratified fluids Peer-reviewed

Yuji Hattori, Makoto Hirota

Journal of Fluid Mechanics　987　2024/05/16
Publisher: Cambridge University Press (CUP)
DOI： 10.1017/jfm.2024.398 　

ISSN： 0022-1120

eISSN： 1469-7645

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The linear stability of the Stuart vortices, which is a model of arrays of vortices often observed in the atmosphere and the oceans, in rotating stratified fluids is investigated by local and modal stability analysis. As in the case of the two-dimensional (2-D) Taylor–Green vortices, five types of instability appear in general: the pure-hyperbolic instability, the strato-hyperbolic instability, the rotational-hyperbolic instability, the centrifugal instability and the elliptic instability. The condition for each instability and the estimate of the growth rate derived by Hattori & Hirota (J. Fluid Mech., vol. 967, 2023, A32) are shown to also be useful for the Stuart vortices, which supports their applicability to general flows. The properties of each instability depend on stratification and rotation in a way similar to the case of the 2-D Taylor–Green vortices. For the Stuart vortices, however, the centrifugal instability and the elliptic instability become more dominant than the three hyperbolic instabilities in comparison to the 2-D Taylor–Green vortices; this is explained by the larger ratios of the maximum vorticity and the strain rate at the elliptic stagnation points to the strain rate at the hyperbolic stagnation points. Direct correspondence between the modal and local stability results is further established by comparing unstable modes to solutions to the local stability equations; this is useful for identifying the types of modes since the mechanism of instability is readily known in the local stability analysis. This helps us to discover the modes of the ring-type elliptic instability, which have been predicted only theoretically.
Turbulence modeling of stratified turbulence using a constrained artificial neural network Peer-reviewed

Daisuke Nishiyama, Yuji Hattori

Physics of Fluids　36　(5)　2024/05/01
Publisher: AIP Publishing
DOI： 10.1063/5.0206650 　

ISSN： 1070-6631

eISSN： 1089-7666
Stability of two-dimensional Taylor–Green vortices in rotating stratified fluids Peer-reviewed

Yuji Hattori, Makoto Hirota

Journal of Fluid Mechanics　967　2023/07/20
Publisher: Cambridge University Press (CUP)
DOI： 10.1017/jfm.2023.513 　

ISSN： 0022-1120

eISSN： 1469-7645

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The linear stability of the two-dimensional Taylor–Green vortices, which is a spatially periodic array of vortices, in rotating stratified fluids is investigated by local and modal stability analysis. Five types of instability appear in general: the pure hyperbolic instability, the strato-hyperbolic instability, the rotational-hyperbolic instability, the centrifugal instability and the elliptic instability. The condition for each instability and the estimate of the growth rate, which are useful in interpreting numerical results, are obtained in the framework of local stability analysis. Realizability of an instability is introduced to predict whether an unstable mode corresponding to an unstable region found in the local stability analysis exists at finite Reynolds numbers. In the absence of stratification, the pure hyperbolic instability is dominant for weak rotation; it is stabilized for strong rotation. For strong anti-cyclonic rotation, the elliptic instability or the centrifugal instability becomes dominant depending on the parameter values; further stronger rotation stabilizes both instabilities. For strong cyclonic rotation, the rotational-hyperbolic instability or the elliptic instability becomes dominant, although the growth rate is smaller than the anti-cyclonic cases. Strong stratification changes the stability properties. The strato-hyperbolic instability occurs for weak rotation. The rotational-hyperbolic instability and the elliptic instability are weakened under cyclonic rotation, while the latter survives and extends the unstable range under anti-cyclonic rotation. The pure hyperbolic instability and the centrifugal instability are less affected by stratification. The mode structures of each instability are in good agreement with the corresponding solution to local stability equations, confirming the physical mechanism of the instability.
A priori assessment of nonlocal data-driven wall modeling in large eddy simulation Peer-reviewed

Golsa Tabe Jamaat, Yuji Hattori

Physics of Fluids　35　(5)　2023/05/01
Publisher: AIP Publishing
DOI： 10.1063/5.0146770 　

ISSN： 1070-6631

eISSN： 1089-7666

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In the present study, a priori assessment is performed on the ability of the convolutional neural network (CNN) for wall-modeling in large eddy simulation. The data used for the training process are provided by the direct numerical simulation (DNS) of the turbulent channel flow. Initially, a study is carried out on the input choices of CNN, and the effect of different flow parameters on establishing a wall model is investigated. Then, the influence of the wall-normal distance on the established data-driven wall model is studied by choosing the CNN input data from two regions of the inner layer (y+&gt;10,y/δ&lt;0.1) and the logarithmic layer. The performance of the obtained CNN wall models based on the inputs from the two regions is further investigated by feeding the network with the data outside the training range. In the next step, the models are tested under various conditions, including a different grid size and a higher Reynolds number. The results show that the models using the inner layer (excluding y+≤10) data as the CNN input have better accuracy in establishing a wall model compared to the models based on the input data in the logarithmic layer, especially when implemented outside the training range. After optimizing the hyperparameters of CNN, a high correlation coefficient of 0.9324 is achieved between the wall shear stress calculated using the filtered DNS data and predicted by the best CNN wall model, which is trained using the data in the inner layer, excluding y+≤10. The performance of the CNN wall model is also compared with the existing wall-stress models, and it is shown that the CNN wall model has better accuracy in establishing a wall model. Additionally, the CNN wall model is shown to have good performance when applied to a different grid size or a higher Reynolds number.
Modal stability analysis of arrays of stably stratified vortices Peer-reviewed

Yuji Hattori, Shota Suzuki, Makoto Hirota, Manish Khandelwal

Journal of Fluid Mechanics　909　2021/02/25
Publisher: Cambridge University Press (CUP)
DOI： 10.1017/jfm.2020.865 　

ISSN： 0022-1120

eISSN： 1469-7645

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Numerical stability analysis of a vortex ring with swirl Peer-reviewed

Yuji Hattori, Francisco J. Blanco-Rodríguez, Stéphane Le Dizès

Journal of Fluid Mechanics　878　5-36　2019/11
Generation of bulk vorticity and current density in current-vortex sheet models Peer-reviewed

Stefan G. Llewellyn Smith, Yuji Hattori

High Energy Density Physics　33　100712　2019
Strato-hyperbolic instability: a new mechanism of instability in stably stratified vortices Peer-reviewed

Shota Suzuki, Makoto Hirota, Yuji Hattori

Journal of Fluid Mechanics　854　293-323　2018/11
Generalized Contour Dynamics: A Review Peer-reviewed

Stefan G. Llewellyn Smith, Ching Chang, Tianyi Chu, Mark Blyth, Yuji Hattori, Hayder Salman

Regular and Chaotic Dynamics　2018/09
Concentration of vorticity due to selective decay in doubly periodic vortices and a vortex pair Peer-reviewed

Yuji Hattori

FLUID DYNAMICS RESEARCH　50　(1)　011405　2018/02

DOI： 10.1088/1873-7005/aa7081 　

ISSN： 0169-5983

eISSN： 1873-7005
Mechanism of aeroacoustic sound generation and reduction in a flow past oscillating and fixedcylinders Peer-reviewed

Yuji Hattori, Ryu Komatsu

JOURNAL OF FLUID MECHANICS　832　241-268　2017/12

DOI： 10.1017/jfm.2017.668 　

ISSN： 0022-1120

eISSN： 1469-7645
Searching for turbulence models by artificial neural network Peer-reviewed

Masataka Gamahara, Yuji Hattori

PHYSICAL REVIEW FLUIDS　2　(5)　2017/05

DOI： 10.1103/PhysRevFluids.2.054604 　

ISSN： 2469-990X
Concentration of vorticity in a destabilized vortex due to selective decay Peer-reviewed

Yuji Hattori

JOURNAL OF FLUID MECHANICS　797　630-643　2016/06

DOI： 10.1017/jfm.2016.304 　

ISSN： 0022-1120

eISSN： 1469-7645
Direct numerical simulation of aeroacoustic sound by volume penalization method Peer-reviewed

Ryu Komatsu, Wakana Iwakami, Yuji Hattori

COMPUTERS & FLUIDS　130　24-36　2016/05

DOI： 10.1016/j.compfluid.2016.02.016 　

ISSN： 0045-7930

eISSN： 1879-0747
Explosive magnetic reconnection caused by an X-shaped current-vortex layer in a collisionless plasma Peer-reviewed

M. Hirota, Y. Hattori, P. J. Morrison

PHYSICS OF PLASMAS　22　(5)　052114　2015/05

DOI： 10.1063/1.4921329 　

ISSN： 1070-664X

eISSN： 1089-7674
Variational necessary and sufficient stability conditions for inviscid shear flow Peer-reviewed

M. Hirota, P. J. Morrison, Y. Hattori

PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES　470　(2172)　20140322　2014/12

DOI： 10.1098/rspa.2014.0322 　

ISSN： 1364-5021

eISSN： 1471-2946
A New Approach for Error Reduction in the Volume Penalization Method Peer-reviewed

Wakana Iwakami, Yuzuru Yatagai, Nozomu Hatakeyama, Yuji Hattori

COMMUNICATIONS IN COMPUTATIONAL PHYSICS　16　(5)　1181-1200　2014/11

DOI： 10.4208/cicp.220513.070514a 　

ISSN： 1815-2406

eISSN： 1991-7120
Evolution of localized disturbances in the elliptic instability Peer-reviewed

Yuji Hattori, Mohd Syafiq bin Marzuki

JOURNAL OF FLUID MECHANICS　755　603-627　2014/09

DOI： 10.1017/jfm.2014.439 　

ISSN： 0022-1120

eISSN： 1469-7645
Density distribution in two-dimensional weakly compressible turbulence Peer-reviewed

Daiki Terakado, Yuji Hattori

PHYSICS OF FLUIDS　26　(8)　2014/08

DOI： 10.1063/1.4892460 　

ISSN： 1070-6631

eISSN： 1089-7666
Modal and non-modal stability of two-dimensional Taylor-Green vortices Peer-reviewed

Takayuki Gau, Yuji Hattori

FLUID DYNAMICS RESEARCH　46　(3)　2014/06

DOI： 10.1088/0169-5983/46/3/031410 　

ISSN： 0169-5983

eISSN： 1873-7005
Modal stability analysis of a helical vortex tube with axial flow Peer-reviewed

Yuji Hattori, Yasuhide Fukumoto

JOURNAL OF FLUID MECHANICS　738　222-249　2014/01

DOI： 10.1017/jfm.2013.591 　

ISSN： 0022-1120

eISSN： 1469-7645
Effects of axial flow on the stability of a helical vortex tube Peer-reviewed

Y. Hattori, Y. Fukumoto

PHYSICS OF FLUIDS　24　(5)　054102-1-054102-15　2012/05

DOI： 10.1063/1.4717769 　

ISSN： 1070-6631
Axisymmetric magnetic vortices with swirl Peer-reviewed

Stefan G. Llewellyn Smith, Y. Hattori

COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION　17　(5)　2101-2107　2012/05

DOI： 10.1016/j.cnsns.2011.06.001 　

ISSN： 1007-5704
Short-wavelength stability analysis of Hill's vortex with/without swirl Peer-reviewed

Y. Hattori, K. Hijiya

PHYSICS OF FLUIDS　22　(7)　074104-1-074104-8　2010/07

DOI： 10.1063/1.3459956 　

ISSN： 1070-6631
Short-wave stability of a helical vortex tube: the effect of torsion on the curvature instability Peer-reviewed

Yuji Hattori, Yasuhide Fukumoto

THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS　24　(1-4)　363-368　2010/03

DOI： 10.1007/s00162-009-0145-2 　

ISSN： 0935-4964
Short-wavelength stability analysis of a helical vortex tube Peer-reviewed

Y. Hattori, Y. Fukumoto

PHYSICS OF FLUIDS　21　(1)　2009/01

DOI： 10.1063/1.3054150 　

ISSN： 1070-6631
Evolution of toroidal magnetic eddies in an ideal fluid Peer-reviewed

Y. Hattori, H. K. Moffatt

JOURNAL OF FLUID MECHANICS　558　253-279　2006/07

DOI： 10.1017/S0022112006000048 　

ISSN： 0022-1120

eISSN： 1469-7645
Reconnexion of vortex and magnetic tubes subject to an imposed strain: An approach by perturbation expansion Peer-reviewed

Y Hattori, HK Moffatt

FLUID DYNAMICS RESEARCH　36　(4-6)　333-356　2005/04

DOI： 10.1016/j.fluiddyn.2005.01.004 　

ISSN： 0169-5983
Curvature instability of a vortex ring Peer-reviewed

Y Fukumoto, J Hattori

JOURNAL OF FLUID MECHANICS　526　77-115　2005/03

DOI： 10.1017/S0022112004002678 　

ISSN： 0022-1120
Shell model for rotating turbulence Peer-reviewed

Y Hattori, R Rubinstein, A Ishizawa

PHYSICAL REVIEW E　70　(4)　046311-1-046311-6　2004/10

DOI： 10.1103/PhysRevE.70.046311 　

ISSN： 1539-3755
Short-wavelength stability analysis of thin vortex rings Peer-reviewed

Y Hattori, Y Fukumoto

PHYSICS OF FLUIDS　15　(10)　3151-3163　2003/10

DOI： 10.1063/1.1606446 　

ISSN： 1070-6631
Axisymmetric acoustic scattering by vortices Peer-reviewed

Y Hattori, SGL Smith

JOURNAL OF FLUID MECHANICS　473　275-294　2002/12

DOI： 10.1017/S002211200200246X 　

ISSN： 0022-1120
Study of reconnection and acoustic emission of quantized vortices in superfluid by the numerical analysis of the Gross-Pitaevskii equation Peer-reviewed

S Ogawa, M Tsubota, Y Hattori

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　71　(3)　813-821　2002/03

DOI： 10.1143/JPSJ.71.813 　

ISSN： 0031-9015
Vortex Reconnection and Acoustic Emission by the Numerical Analysis of the Gross-Pitaevskii Equation Peer-reviewed

M. Tsubota, S. Ogawa, Y. Hattori

Journal of Low Temperature Physics　121　435-440　2001
Sound generation by coaxial collision of two vortex rings Peer-reviewed

O Inoue, Y Hattori, T Sasaki

JOURNAL OF FLUID MECHANICS　424　327-365　2000/12

DOI： 10.1017/S0022112000002123 　

ISSN： 0022-1120
Asymptotic analysis of radiation extinction of stretched premixed flames Peer-reviewed

Y Ju, G Masuya, F Liu, Y Hattori, D Riechelmann

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER　43　(2)　231-239　2000/01

DOI： 10.1016/S0017-9310(99)00130-1 　

ISSN： 0017-9310
Sound generation by shock-vortex interactions Peer-reviewed

O Inoue, Y Hattori

JOURNAL OF FLUID MECHANICS　380　81-116　1999/02

DOI： 10.1017/S0022112098003565 　

ISSN： 0022-1120
Large coherent structure formation by magnetic stretching term in two-dimensional MHD turbulence Peer-reviewed

A Ishizawa, Y Hattori

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　67　(12)　4302-4303　1998/12

DOI： 10.1143/JPSJ.67.4302 　

ISSN： 0031-9015
Wavelet analysis of two-dimensional MHD turbulence Peer-reviewed

A Ishizawa, Y Hattori

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　67　(2)　441-450　1998/02

DOI： 10.1143/JPSJ.67.441 　

ISSN： 0031-9015
MOTION OF FLUID PARTICLES AND STRETCHING OF LINE ELEMENTS OF AN IDEAL FLUID Peer-reviewed

Y HATTORI, T KAMBE

FLUID DYNAMICS RESEARCH　13　(2)　97-117　1994/02

DOI： 10.1016/0169-5983(94)90009-4 　

ISSN： 0169-5983
IDEAL MAGNETOHYDRODYNAMICS AND PASSIVE SCALAR MOTION AS GEODESICS ON SEMIDIRECT PRODUCT GROUPS Peer-reviewed

Y HATTORI

JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL　27　(2)　L21-L25　1994/01

DOI： 10.1088/0305-4470/27/2/004 　

ISSN： 0305-4470
Dimension estimate of the global attractor for forced oscillation systems Peer-reviewed

Yuji Hattori, Naoyuki Ishimura, Isamu Ohnishi, Makoto Umeki

Japan Journal of Industrial and Applied Mathematics　10　(3)　351-366　1993/10

DOI： 10.1007/BF03167279 　

ISSN： 0916-7005 1868-937X
CROSS HELICITY AND ALIGNMENT STRUCTURE IN 2-DIMENSIONAL MHD TURBULENCE Peer-reviewed

Y HATTORI

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　62　(8)　2541-2544　1993/08

DOI： 10.1143/JPSJ.62.2541 　

ISSN： 0031-9015
EFFECT OF PHASE-DEPENDENT INVARIANTS AND ERGODICITY IN FINITE-MODE SYSTEMS CLOSELY-RELATED WITH 2-DIMENSIONAL IDEAL FLOW Peer-reviewed

Y HATTORI

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　62　(7)　2293-2305　1993/07

DOI： 10.1143/JPSJ.62.2293 　

ISSN： 0031-9015
GEODESICS AND CURVATURE OF A GROUP OF DIFFEOMORPHISMS AND MOTION OF AN IDEAL FLUID Peer-reviewed

F NAKAMURA, Y HATTORI, T KAMBE

JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL　25　(2)　L45-L50　1992/01

DOI： 10.1088/0305-4470/25/2/003 　

ISSN： 0305-4470
Effect of Wall Temperature and Transpiration on Gortler Vortices in High-speed Boundary Layers

Asmaa Ahaggach, Adrian Sescu, Zamir Koshuriyan, Yuji Hattori

Proceedings of the Twenty-Second International Conference on Flow Dynamics　1180-1183　2025/11
DNS Investigation of the Mechanics of Gortler Vortices Breakdown in Hypersonic Flows

Omar Es-Sahli, Matthew Brockhaus, Adrian Sescu, Zamir Koshuriyan, Yuji Hattori

Proceedings of the Twenty-Second International Conference on Flow Dynamics　1176-1179　2025/11
Global Stability Analysis of Boundary Layer Flow Over Complex Roughness Modeled by the Volume Penalization Method

Hinata Fujii, Makoto Hirota, Yuji Hattori

Proceedings of the Twenty-Second International Conference on Flow Dynamics　1172-1175　2025/11
Nonlinear Dynamics and Turbulent Transition of a Helical Vortex Disturbed by the Short-wave Instabilities

Daisuke Nishiyama, Yuji Hattori

Proceedings of the Twenty-Second International Conference on Flow Dynamics　1167-1169　2025/11
Shortwave Instability of Helical Vortices with Swirl

Ivan Delbende, Yuji Hattori, Maurice Rossi

Proceedings of the Twenty-Second International Conference on Flow Dynamics　1163-1166　2025/11
Vortex Merging Triggered by Hyperbolic Instability of 2D Taylor-Green Vortex

Makoto Hirota, Naoya Ueno, Yuji Hattori

Proceedings of the Twenty-Second International Conference on Flow Dynamics　1160-1162　2025/11
The Sound-Vortex Feedback Loop underWing-in-Ground Effect

Liangkui Tan, Yuji Hattori

Proceedings of the Twenty-Second International Conference on Flow Dynamics　1130-1133　2025/11
Analysis of Coarse-grained Turbulent Vorticity Fields at High Reynolds Numbers using Large-scale DNS

Takashi Ishihara, Yoshinobu Kanao, Yuji Hattori

Proceedings of the Twenty-Second International Conference on Flow Dynamics　1128-1129　2025/11
Residual-Based Diffusion Model for High-Resolution Flow Field Reconstruction

Golsa Tabe Jamaa, Takayuki Okatani, Yuji Hattori

Proceedings of the Twenty-Second International Conference on Flow Dynamics　1120-1123　2025/11
A numerical procedure to study the stability of helical vortices Peer-reviewed

Yonghui Xu, Ivan Delbende, Yuji Hattori, Maurice Rossi

Theoretical and Computational Fluid Dynamics　39　(1)　2025/02

DOI： 10.1007/s00162-024-00734-w 　

ISSN： 0935-4964

eISSN： 1432-2250
Shape optimization of an air-jet instrument using the continuous adjoint method Peer-reviewed

Ryoya Tabata, Kensuke Okada, Tetsuro Shoji, Keita Arimoto, Yuji Hattori

Proceedings of Meetings on Acoustics　58　035009-035009　2025
Publisher: ASA
DOI： 10.1121/2.0002087 　

ISSN： 1939-800X
Applicability criteria of proper charge neutrality and special relativistic MHD models extended by two-fluid effects Peer-reviewed

Shuntaro Yoshino, Makoto Hirota, Yuji Hattori

Physics of Plasmas　31　(12)　2024/12/01

DOI： 10.1063/5.0243293 　

ISSN： 1070-664X

eISSN： 1089-7674
Streamwise-Elongated Sinusoidal Roughness Elements with Enhanced Laminarizing Effect on Three-Dimensional Boundary Layer Peer-reviewed

Makoto Hirota, Yuki Ide, Yuji Hattori

AIAA Journal　62　(10)　3672-3685　2024/10

DOI： 10.2514/1.J064044 　

ISSN： 0001-1452

eISSN： 1533-385X
Assessment of Turbulence Models for Cylinder Flow Aeroacoustics Peer-reviewed

Xiao Wang, Shanti Bhushan, Adrian Sescu, Edward Luke, Bukhari Manshoor, Yuji Hattori

Aerospace　11　(9)　2024/09

DOI： 10.3390/aerospace11090707 　

eISSN： 2226-4310
Effect of pitch on nonlinear dynamics of helical vortex disturbed by long-wave instability Peer-reviewed

Yuji Hattori, Akihiro Hirano

Journal of Fluid Mechanics　991　2024/08/20

DOI： 10.1017/jfm.2024.529 　

ISSN： 0022-1120

eISSN： 1469-7645
A posteriori study on wall modeling in large eddy simulation using a nonlocal data-driven approach Peer-reviewed

Golsa Tabe Jamaat, Yuji Hattori, Soshi Kawai

Physics of Fluids　36　(6)　2024/06/01

DOI： 10.1063/5.0210851 　

ISSN： 1070-6631

eISSN： 1089-7666
Gauging Centrifugal Instabilities in Compressible Free-Shear Layers via Nonlinear Boundary Region Equations Peer-reviewed

Omar Es-Sahli, Adrian Sescu, Yuji Hattori

Fluids　9　(5)　112-112　2024/05/11
Publisher: MDPI AG
DOI： 10.3390/fluids9050112 　

eISSN： 2311-5521
Design Basis of Sinusoidal Roughness Elements for Enhanced Laminarizing Effect on Three-dimensional Boundary Layer

Makoto Hirota, Yuki Ide, Yuji Hattori

AIAA SciTech Forum and Exposition, 2024　2024

DOI： 10.2514/6.2024-0889 　
Effect of streamwise pressure gradients on Görtler vortices in high-speed boundary layers

Omar Es Sahli, Adrian Sescu, Yuji Hattori

AIAA SciTech Forum and Exposition, 2024　2024

DOI： 10.2514/6.2024-1566 　
Breakdown of Görtler vortices in high-speed boundary layer flows: a DNS study

Matthew Brockhaus, Adrian Sescu, Omar Es-Sahli, Yuji Hattori

AIAA Aviation Forum and ASCEND, 2024　2024

DOI： 10.2514/6.2024-3533 　
On the Self-similarity Behaviour of Coherent Structures in a Fully-developed Axisymmetric Turbulent Wake

Yi Zhou, Yasumasa Ito, Koji Nagata, Tomoaki Watanabe, Koji Iwano, Yasuhiko Sakai, Yuji Hattori

23rd International Symposium on Advanced Fluid Information　2023/11
An Analysis of Self-organization of Three Dimensional Vortical Structure Derived from Interaction between Vortical Flow and Bundle of Vorticity Lines

Katsuyuki Nakayama, Kaito Uchima, Yuji Hattori

23rd International Symposium on Advanced Fluid Information　2023/11
Study of Turbulent Transition and Statistical Properties of Turbulence of Destabilized Helical Vortex

Yuji Hattori, Ivan Delbende, Maurice Rossi

23rd International Symposium on Advanced Fluid Information　2023/11
Quasi-Steady State of a Hub Vortex Under Multi-Polar Strain Induced by Satellite Vortices

Aditya Sai, Pranith Ayapilla, Yuji Hattori

20th International Conference on Flow Dynamics　1025-1028　2023/11
Nonlinear Development of Instability of Two-Dimensional Taylor-Green Vortices in Rotating Fluid

Naoya Ueno, Makoto Hirota, Yuji Hattori

20th International Conference on Flow Dynamics　1020-1022　2023/11
Linear Short-Wave Instability in Helical Vortices

Ivan Delbende, Yuji Hattori, Maurice Rossi, Yonghui Xu

20th International Conference on Flow Dynamics　1017-1019　2023/11
Numerical Study on Fundamental Process of a Thermoacoustic Engine

Yo Tashima, Taijiro Ohno, Takeshi Nanri, Taizo Kobayashi, Yuji Hattori, Kin’ya Takahashi

20th International Conference on Flow Dynamics　1009-1011　2023/11
Numerical Study on Sound Generation Process of an Oboe Reeds with DNS

Yuki Nakahara, Rei Sumita, Ryoya Tabata, Sho Iwagami, Takeshi Nanri, Taizo Kobayashi, Yuji Hattori, Kin’ya Takahashi

20th International Conference on Flow Dynamics　1006-1008　2023/11
Streamwise Pressure Gradient Effect on Görtler Vortices: a Numerical Study in the Compressible Regime

Omar Es-Sahli, Adrian Sescu, Zamir Koshuriyan, Yuji Hattori

20th International Conference on Flow Dynamics　998-1001　2023/11
Evaluation of Noise Generated from Turbulent Boundary Layer on a Flat Plate Using Direct Numerical Simulation

Natsumi Hirao, Makoto Hirota, Yuji Hattori

20th International Conference on Flow Dynamics　987-989　2023/11
Investigating a Non-local Data-Driven Approach for Wall Modeling in Large Eddy Simulation

Golsa Tabe Jamaat, Yuji Hattori

20th International Conference on Flow Dynamics　956-959　2023/11
Relation between Turbulence in Swirling Flow in a Cylindrical Pipe and The Ranque-Hilsch Effect

Taihei Yamamoto, Yuji Hattori

20th International Conference on Flow Dynamics　937-940　2023/11
A data-driven approach to model enstrophy transfers in large eddy simulation of forced two-dimensional turbulence Peer-reviewed

Aditya Sai, Pranith Ayapilla, Yuji Hattori

Physics of Fluids　35　(7)　2023/07/01
Publisher: AIP Publishing
DOI： 10.1063/5.0153735 　

ISSN： 1070-6631

eISSN： 1089-7666

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Contemporary research on the application of data-driven techniques to modeling subgrid closure in two-dimensional turbulence has been limited. Furthermore, the incorporation of the enstrophy cascade and other two-dimensional turbulence-specific physics has received insufficient attention. To address these gaps, a novel physics-based shallow feed-forward neural network framework was designed in this study to model subgrid closure in three selected cases of forced two-dimensional turbulence with a forcing that provides energy and enstrophy at a particular wavenumber. As a novel approach, we trained our framework to learn the subgrid vorticity transport vector from a set of appropriate resolved flow variables. Another framework used in recent works which directly learned the subgrid forcing field was also investigated. Both frameworks were assessed using a priori and a posteriori tests for two selected filter widths. Both frameworks performed accurately for the lower filter width but less accurately for the higher filter width. However, we demonstrate that our new framework has wider usefulness for model diagnosis. Ad hoc clipping procedures were used to make the models more generalizable to higher filter widths, and stable and consistent a posteriori tests were observed for all test cases and filter widths when the subgrid forcing field was modified to enhance the model's subgrid dissipative characteristics. In contrast, modifying the enstrophy fluxes did not perform as consistently. These findings demonstrate the potential of the novel physics-based framework for improving subgrid modeling in two-dimensional turbulence.
Appearance of the −5/3 scaling law in spatially intermittent flows with strong vortex shedding Peer-reviewed

Physics of Fluids　35　(4)　2023/04/01
Publisher: AIP Publishing
DOI： 10.1063/5.0141076 　

ISSN： 1070-6631

eISSN： 1089-7666

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Our previous investigations [“Extreme events and non-Kolmogorov -5/3 spectra in turbulent flows behind two side-by-side square cylinders,” J. Fluid Mech. 874, 677–698 (2019); “Energy transfer in turbulent flows behind two side-by-side square cylinders,” J. Fluid Mech. 903, A4 (2020)] revealed that an extended −5/3 energy spectrum can be found in the highly intermittent flow accompanied by strong vortex shedding (i.e., composed of both large-scale laminar and turbulent motions). To shed light on the emergence of the −5/3 energy spectra, we perform direct numerical simulations of a single-cylinder wake. In the highly intermittent upstream region, albeit a significant −5/3 scaling law can be found, the energy spectra and the corresponding Kolmogorov constant Ck are distinctly different from those in the downstream almost turbulent region and the case of grid turbulence with a similar local Reynolds number. However, the conditional Kolmogorov constant acquires the expected value and the conditional energy spectra are in good agreement with those in the far downstream region. Ck is found to have a power-law dependence on the intermittency factor γ, C k ∼ γ 1 / 3. This study, the first of its kind, demonstrates that in the highly intermittent flow, the composed turbulent motions are responsible for the emergence of the −5/3 scaling law, which implies the characteristics of the composed turbulent motions resemble those in the fully turbulent flow.
Scale-by-scale analysis of interscale scalar transfer in grid turbulence with mean scalar gradient Peer-reviewed

Muyang Wang, Takuya Yurikusa, Koji Iwano, Yasuhiko Sakai, Yasumasa Ito, Yi Zhou, Yuji Hattori

Physics of Fluids　35　(4)　2023/04/01
Publisher: AIP Publishing
DOI： 10.1063/5.0145314 　

ISSN： 1070-6631

eISSN： 1089-7666

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Direct numerical simulations were carried out on grid turbulence with a mean scalar gradient to reveal interscale scalar transport. Two-point statistical analysis using the structure function and the scale-by-scale scalar equation was performed. Results show that the third-order structure function becomes negative at large scales in the upstream region (inverse cascade occurs), while such distributions do not appear for turbulence energy. This phenomenon in scalars gradually disappears in the downstream region. Budget analysis of the structure function reveals that this is mainly caused by the non-linear scalar transfer term in the direction of the mean scalar gradient (vertical direction here). When the separation distance is smaller than Taylor's microscale, where the interscale scalar transfer is normal (large to small scales), the direction of the scalar flux is determined by the vertical velocity fluctuation difference between two points. However, when separation is larger than Taylor's microscale and inverse cascading occurs, the direction is determined by derivative of the scalar fluctuation rather than the velocity fluctuation difference. Further analysis reveals that the existence of fluid mass with an unmixed scalar plays an important role in the inverse cascade phenomenon.
Lagrange Multiplier-Based Optimal Control Technique for Streak Attenuation in High-Speed Boundary Layers Peer-reviewed

Omar Es-Sahli, Adrian Sescu, M. Zamir A. Koshuriyan, Yuji Hattori, Makoto Hirota

AIAA Journal　61　(1)　63-75　2023/01
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
DOI： 10.2514/1.j062255 　

ISSN： 0001-1452

eISSN： 1533-385X

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High-amplitude freestream turbulence and surface roughness elements can excite a laminar boundary-layer flow sufficiently to cause streamwise-oriented vortices to develop. These vortices resemble elongated streaks having alternate spanwise variations of the streamwise velocity. Downstream, the vortices “wobble” through an inviscid secondary instability mechanism and, ultimately, transition to turbulence. We formulate an optimal control algorithm to suppress the growth rate of the streamwise vortex system. Considering a high-Reynolds-number asymptotic framework, we reduce the full compressible Navier–Stokes equations to the nonlinear compressible boundary-region equations. We then implement the method of Lagrange multipliers via an appropriate transformation of the original constrained optimization problem into an unconstrained form to obtain the disturbance equations in the form of the adjoint compressible boundary-region equations (ACBREs) and corresponding optimality conditions. Numerical solutions of the ACBRE approach for high-supersonic and hypersonic flows reveal a significant reduction in the kinetic energy and wall shear stress for all considered configurations. We present contour plots to demonstrate the qualitative effect of increased control iterations. Our results indicate that the primary vortex instabilities gradually flatten in the spanwise direction thanks to the ACBRE algorithm.
Searching for a Wall Model in LES using a Data-Driven Approach

G. Tabe Jamaa, Y. Hattori

Nineteenth International Conference on Flow Dynamics　2022/11
Validation of Special Relativistic Magnetohydrodynamics Models by Scale Analysis

S. Yoshino, M. Hirota, Y. Hattori

Nineteenth International Conference on Flow Dynamics　2022/11
Laminarization of Three-Dimensional BoundaryLayer by Artificially-Sustained Crossflow Vortices

M. Hirota, Y. Ide, Y. Hattori

Nineteenth International Conference on Flow Dynamics　2022/11
Aeroacoustic analysis of oboe reeds with compressible direct numerical simulation Peer-reviewed

Yuki NAKAHARA, Rei SUMITA, Ryoya TABATA, Sho IWAGAMI, Takeshi NANRI, Taizo KOBAYASHI, Yuji HATTORI, Kin’ya TAKAHASHI

Proceedings of the 24th International Congress on Acoustics　2022/10
Numerical study of a French horn mouthpiece accompanied by vibrating lips and an oral cavity with compressible direct numerical simulation Peer-reviewed

Rei SUMITA, Ryoya TABATA, Sho IWAGAMI, Yuki NAKAHARA, Takeshi NANRI, Taizo KOBAYASHI, Yuj HATTORI, Kin’ya Takahashi

Proceedings of the 24th International Congress on Acoustics　2022/10
Interscale transfer of turbulent energy in grid-generated turbulence with low Reynolds numbers Peer-reviewed

Muyang Wang, Takuya Yurikusa, Yasuhiko Sakai, Koji Iwano, Yasumasa Ito, Yi Zhou, Yuji Hattori

International Journal of Heat and Fluid Flow　97　109031-109031　2022/10
Publisher: Elsevier BV
DOI： 10.1016/j.ijheatfluidflow.2022.109031 　

ISSN： 0142-727X
Modeling of Crossflow-Induced Boundary Layer Transition Peer-reviewed

Makoto Hirota, Yuki Ide, Yuji Hattori

Lecture Notes in Electrical Engineering　395-408　2022/08/31
Publisher: Springer Nature Singapore
DOI： 10.1007/978-981-19-2689-1_30 　

ISSN： 1876-1100

eISSN： 1876-1119
Development of subgrid-scale model for LES of Burgers turbulence with large filter size Peer-reviewed

Golsa Tabe Jamaat, Yuji Hattori

Physics of Fluids　34　(4)　045120-045120　2022/04
Publisher: AIP Publishing
DOI： 10.1063/5.0087761 　

ISSN： 1070-6631

eISSN： 1089-7666

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A neural network (NN) with one hidden layer is implemented to establish a relationship between the resolved-scale flow field and the subgrid-scale (SGS) stress for large eddy simulation (LES) of the Burgers equation. Five sets of input are considered for the neural network by combining the velocity gradient and the filter size. The training datasets are obtained by filtering the direct numerical simulation (DNS) results of the Burgers equation with random forcing function. The number of modes is sufficiently large ( N = 65 536) to resolve extremely small scales of motion. In the a priori test, a correlation coefficient over 0.93 is achieved for the SGS stress between the NN models and the filtered DNS data. The results of the a posteriori test reveal that the obtained solutions are stable for all NN models without applying any stabilization techniques. However, not all NN models have a reasonable performance when embedded in the LES code. The applicability of the NN models to the Burgers equation with higher and lower viscosity is also investigated, and it is indicated that the most reliable NN models obtained in this paper can be applied to a set of parameters which are different from those used in training. The results of the SGS models constructed using the neural network are also compared with the existing models, and it is shown that the best obtained NN models outperform the Smagorinsky model and the gradient model, and are comparable to the dynamic Smagorinsky model. However, the NN models have an advantage over the dynamic Smagorinsky model in numerical cost.
Investigation of Görtler vortices in high-speed boundary layers via an efficient numerical solution to the non-linear boundary region equations Peer-reviewed

Omar Es-Sahli, Adrian Sescu, Mohammed Afsar, Yuji Hattori

Theoretical and Computational Fluid Dynamics　36　(2)　237-249　2022/04
Publisher: Springer Science and Business Media LLC
DOI： 10.1007/s00162-021-00576-w 　

ISSN： 0935-4964

eISSN： 1432-2250
A Coupled LES-Synthetic Turbulence Method for Jet Noise Prediction Peer-reviewed

Joshua D. Blake, Adrian Sescu, David Thompson, Yuji Hattori

Aerospace　9　(3)　171-171　2022/03/21
Publisher: MDPI AG
DOI： 10.3390/aerospace9030171 　

eISSN： 2226-4310

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Large-eddy simulation (LES)-based jet noise predictions do not resolve the entire broadband noise spectra, often under-predicting high frequencies that correspond to un-resolved small-scale turbulence. The coupled LES-synthetic turbulence (CLST) model is presented which aims to model the missing high frequencies. The CLST method resolves large-scale turbulent fluctuations from coarse-grid large-eddy simulations (CLES) and models small-scale fluctuations generated by a synthetic eddy method (SEM). Noise is predicted using a formulation of the linearized Euler equations (LEE), where the acoustic waves are generated by source terms from the combined fluctuations of the CLES and the stochastic fields. Sweeping and straining of the synthetic eddies are accounted for by convecting eddies with the large turbulent scales from the CLES flow field. The near-field noise of a Mach 0.9 jet at a Reynolds number of 100,000 is predicted with LES. A high-order numerical algorithm, involving a dispersion relation preserving scheme for spatial discretization and an Adams–Bashforth scheme for time marching, is used for both LES and LEE solvers. Near-field noise spectra from the LES solver are compared to published results. Filtering is applied to the LES flow field to produce an under-resolved CLES flow field, and a comparison to the un-filtered LES spectra reveals the missing noise for this case. The CLST method recovers the filtered high-frequency content, agreeing well with the spectra from LES and showing promise at modeling the high-frequency range in the acoustic noise spectrum at a reasonable expense.
Optimization of turbulent transition delay effect using quasi-statically transforming wall roughness shape Peer-reviewed

Takayuki SHIROSAKI, Makoto HIROTA, Yuji HATTORI

Journal of Fluid Science and Technology　17　(3)　JFST0010-JFST0010　2022
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/jfst.2022jfst0010 　

eISSN： 1880-5558
Mechanism of reduction of aeroacoustic sound by porous material: Comparative study of microscopic and macroscopic models

Yasunori Sato, Yuji Hattori

Journal of Fluid Mechanics　929　2021/12/25
Publisher: Cambridge University Press
DOI： 10.1017/jfm.2021.884 　

ISSN： 1469-7645 0022-1120
Numerical Study on Sounding Mechanism of Air-Jet Instruments with Compressible Fluid Simulation

Kin’ya Takahashi, Ryoya Tabata, Sho Iwagami, Shiryu Ikoga, Rei Sumita, Shota Takanami, Taizo Kobayashi, Yuji Hattori

Eighteenth International Conference on Flow Dynamics　2021/10
Characteristics of Inertial Waves on Axisymmetric Vortex

Tetsuya Abe, Yuji Hattori

Eighteenth International Conference on Flow Dynamics　2021/10
Optimization of Turbulent Transition Delay Effect Using Dynamically Transforming Roughness Elements

Takayuki Shirosaki, Makoto Hirota, Yuji Hattori

Eighteenth International Conference on Flow Dynamics　2021/10
Numerical Study on Local Scale Similarity of Primary and Secondary Crossflow Instability

Makoto Hirota, Yuki Ide, Yuji Hattori

Eighteenth International Conference on Flow Dynamics　2021/10
Searching for Subgrid-Scale Model for Burgers Equation Using Neural Network

Golsa Tabe Jamaat, Yuji Hattori

Eighteenth International Conference on Flow Dynamics　2021/10
Numerical study on edge tone with compressible direct numerical simulation: Sound intensity and jet motion Peer-reviewed

Sho Iwagami, Ryoya Tabata, Taizo Kobayashi, Yuji Hattori, Kin’ya Takahashi

International Journal of Aeroacoustics　1475472X2110032-1475472X2110032　2021/03/24
Publisher: SAGE Publications
DOI： 10.1177/1475472x211003296 　

ISSN： 1475-472X

eISSN： 2048-4003

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A two-dimensional model of the edge tone is studied by a highly accurate and reliable method of direct numerical simulation of the compressible Navier-Stokes equations, and used to verify key features observed in previous experimental and numerical studies, and to discover new features related to the jet motion and the edge tone generation mechanism. The first and second modes of the edge tone that are numerically reproduced agree well with Brown’s equation. In the mode transition region, dynamical mode transition is observed at a fixed jet velocity. For both first and second modes, the pressure distributions are antisymmetric with respect to the edge plate, and the sound intensity is proportional to the fifth power of the jet velocity. These results are consistent with the edge tone being radiated from a dipole-like source. Spatial profiles of the velocity and the velocity variance of the oscillating jet are also investigated for each mode over a range of the jet velocity including the mode transition regime. The amplitude of the velocity oscillation becomes constant with increasing jet velocity, while a measure of the amplitude of the velocity variance profile, which is introduced to characterize the strength of the jet fluctuation and named the ’fluctuation strength’, is proportional to the third power of the jet velocity. Some properties of the fluctuation strength correspond to properties of the sound intensity, including the first mode having larger amplitude than the second mode, and the way of deviating from the power law at smaller values of jet velocity and in the mode transition region. It is proposed that the third-power law exhibited by behavior of the fluctuation strength could be related to the increase of the skewness observed in the velocity profile with increase of jet velocity, and a model calculation is used to support this proposal.
Effect of localized wall cooling or heating on streaks in high-speed boundary layers

Omar Es-Sahli, Adrian Sescu, Mohammed Z. Afsar, Yuji Hattori, Makoto Hirota

AIAA Scitech 2021 Forum　2021/01/11
Publisher: American Institute of Aeronautics and Astronautics
DOI： 10.2514/6.2021-0853 　
A compressible boundary layer optimal control approach using nonlinear boundary region equations

Omar Es-Sahli, Adrian Sescu, Mohammed Afsar, Yuji Hattori, Makoto Hirota

AIAA Aviation and Aeronautics Forum and Exposition, AIAA AVIATION Forum 2021　2021

DOI： 10.2514/6.2021-2945 　
Control of Görtler Vortices in High-Speed Boundary Layer Flows Using Nonlinear Boundary Region Equations

Omar Es-Sahli, Adrian Sescu, Mohammed Z. Afsar, Yuji Hattori, Makoto Hirota

Eighteenth International Conference on Flow Dynamics　2021
Structures of wing-tip vortices at low Reynolds numbers and their modelling Peer-reviewed

Hiroshi Koizumi, Yuji Hattori

Fluid Dynamics Research　52　(4)　045503-045503　2020/07/09
Publisher: IOP Publishing
DOI： 10.1088/1873-7005/ab9b63 　

eISSN： 1873-7005
Streaks in high-speed boundary layers: Assessment via the full nonlinear boundary-region equations

Adrian Sescu, Mohammed Afsar, Yuji Hattori

AIAA Scitech 2020 Forum　1　2020
Publisher: American Institute of Aeronautics and Astronautics Inc, AIAA
DOI： 10.2514/6.2020-0830 　
Dynamic geometrical analysis of high-enstrophy structures in isotropic turbulence

Yuji Hattori, Takashi Ishihara

ETC 2013 - 14th European Turbulence Conference　2020
Assessment of immersed boundary method as a tool for direct numerical simulation of aeroacoustic sound Peer-reviewed

Kosei NISHIKAWA, Kodai KONNO, Yuji Hattori

Journal of Fluid Science and Technology　15　(1)　JFST0004　2020/01
Development of Efficient Method for Aerodynamic Analysis by Machine Learning

Akitaka Toyota, Yuji Hattori

Proceedings of the Sixteenth International Conference on Flow Dynamics　742-743　2019/11
An Investigation of Topological Analysis of Vortical Structure in a Channel Flow2

Keita Kondo, Katuyuki Nakayama, Yuji Hattori

Proceedings of the Sixteenth International Conference on Flow Dynamics　722-723　2019/11
Stretching Effect for Swirling in Eigen-Vortical-Axis Lines in a Hierarchal Isotropic Homogeneous Turbulence

Hayato Hori, Katsuyuki Nakayama, Yuji Hattori

Proceedings of the Sixteenth International Conference on Flow Dynamics　16th　682-683　2019/11
Numerical Studies on Structure of Jupiter's Great Red Spot based on Simplified Model

Ryo Nakazawa, Yuji Hattori

Proceedings of the Sixteenth International Conference on Flow Dynamics　674-675　2019/11
Numerical Simulation of Vertical Vorticity Generation in Unstable Stratified Shear Flow

Akira Takahashi, Makoto Hirota, Yuji Hattori

Proceedings of the Sixteenth International Conference on Flow Dynamics　672-673　2019/11
Numerical Study on Relation between the Jet Oscillation and Acoustic Pressure in Edge Tone

Sho Iwagami, Ryoya Tabata, Taizo Kobayashi, Kin’ya Takahashi, Yuji Hattori

Proceedings of the Sixteenth International Conference on Flow Dynamics　660-661　2019/11
Streak Growth in High-Speed Boundary Layers: Assessment through the Compressible Boundary Region Equations

Adrian Sescu, Mohammed Z. Afsar, Yuji Hattori

Proceedings of the Sixteenth International Conference on Flow Dynamics　658-659　2019/11
Scale Analysis for Primary and Secondary Instabilities of Three-dimensional Boundary Layer,

Makoto Hirota, Yuki Ide, Takahisa Hayashida, Yuji Hattori

Proceedings of the Sixteenth International Conference on Flow Dynamics　656-657　2019/11
Multiscale Flow and Interfacial Transport Phenomena at Phase and Material Boundaries

Shigeru Obayashi, Yuji Hattori, embers

Proceedings of the 18th International Symposium on Advanced Fluid Information　192-193　2018/11
Instability and Nonlinear Dynamics of Curved Vortices

Yuji Hattori, Makoto Hirota, Stéphane Le Dizès, Thomas Leweke, Stefan, G. Llewellyn Smith, Ivan Delbende, Maurice Rossi, Yasuhide Fukumot

Proceedings of the 18th International Symposium on Advanced Fluid Information　190-191　2018/11
Aeroacoustics of Low Reynolds Number Flows Via Dynamic Hybrid RANS/LES and DNS

Xiao Wang, Shanti Bhushan, Edward Luke, David Thompson, Adrian Sescu, Yuji Hattori

Proceedings of the 18th International Symposium on Advanced Fluid Information　180-181　2018/11
Numerical Study on Aeolian Tone with Compressible LES

Hirokazu Yokoyama, Sho Iwagami, Taizo Kobayashi, Kin’ya Takahashi, Yuji Hattori

Proceedings of the 18th International Symposium on Advanced Fluid Information　178-179　2018/11
Applications of the Analysis of Turbulence Structure Using Eigenvectors of Rate-of-strain Tensor

Takashi Ishihara, Gerrit E. Elsinga, Yuji Hattori

Proceedings of the 18th International Symposium on Advanced Fluid Information　154-155　2018/11
Suppression Mechanism of Crossflow Vortices in a Three-dimensional Boundary Layer by Triggering Less Unstable Modes

Makoto Hirota, Yuji Hattori

Proceedings of the Fifteenth International Conference on Flow Dynamics　818-819　2018/11
Suppression of Instability in Boundary Layer on Swept Wing by DRE

Takahisa Hayashida, Makoto Hirota, Yuji Hattori

Proceedings of the Fifteenth International Conference on Flow Dynamics　816-817　2018/11
Modeling of Porous Materials for Numerical Study of Aeroacoustic Noise Reduction

Yasunori Sato, Yuji Hattori

Proceedings of the Fifteenth International Conference on Flow Dynamics　810-811　2018/11
Numerical Simulation of Porous Wing and Flap: Aerodynamic Performance and Noise Reduction

Takumi Watarai, Yuji Hattori

Proceedings of the Fifteenth International Conference on Flow Dynamics　808-809　2018/11
Mode Jump of Edge Tone Captured by Direct Numerical Simulation

Sho Iwagami, Taizo Kobayashi, Kin’ya Takahashi, Yuji Hattori

Proceedings of the Fifteenth International Conference on Flow Dynamics　806-807　2018/11
Enhancing Jet Turbulence and Acoustics via a Coupled LES - Stochastic Model

Joshua Blake, Adrian Sescu, David Thompson, Yuji Hattori

Proceedings of the Fifteenth International Conference on Flow Dynamics　780-781　2018/11
Dynamic hybrid RANS/LES assessment of sound generation and propagation from flow over a circular cylinder Peer-reviewed

Xiao Wang, Shanti Bhushan, Bukhari Manshoor, Edward Luke, Adrian Sescu, Yuji Hattori, David Thompson, Keith Walters

Proceedings of 2018 AIAA/CEAS Aeroacoustics Conference　2018/06
A coupled LES/stochastic modeling approach to jet noise prediction Peer-reviewed

Joshua Blake, Adrian Sescu, David Thompson, Yuji Hattori

AIAA Aerospace Sciences Meeting, 2018　(210059)　2018
Publisher: American Institute of Aeronautics and Astronautics Inc, AIAA
DOI： 10.2514/6.2018-1248 　
Corrected Volume Penalization Method for Direct Numerical Simulation of Compressible Flow and Aeroacoustic Sound

Yuji Hattori

Proceedings of Japan-Korea CFD workshop (JKCFD2017)　201-203　2017/11/10
SGS Stress Regression by Neural Network in Isotropic Homogeneous Turbulence

Satoshi Miyazaki, Yuji Hattori

Proceedings of the Fourteenth International Conference on Flow Dynamics　606-607　2017/11
Numerical Study of Wing Noise Reduction by Using Porous Flap

Takumi Watarai, Yuji Hattori

Proceedings of the Fourteenth International Conference on Flow Dynamics　574-575　2017/11
Linear Instability of Compressible Vortex Pair with Axial Flow

Tomohiro Sawa, Yuji Hattori, Makoto Hirota

Proceedings of the Fourteenth International Conference on Flow Dynamics　588-589　2017/11
Instability and Nonlinear Dynamics of Curved Vortices

Y. Hattori, M. Hirota, S. Dizes, T. Leweke, S. G. Llewellyn Smith, Y. Fukumoto

Proceedings of the 17th International Symposium on Advanced Fluid Information　192-193　2017/11
Hyperbolic Instability of Stratified Vortices

Manish K Khandelwal, Shota Suzuki, Makoto Hirota, Yuji Hattori

Proceedings of the Fourteenth International Conference on Flow Dynamics　590-591　2017/11
Fundamental Mechanism of Fluid-Acoustic Interaction in Edge Tone

Sho Iwagami, Taizo Kobayashi, Kin’ya Takahashi, Yuji Hattori

Proceedings of the 17th International Symposium on Advanced Fluid Information　10-11　2017/11
Aeroacoustics of Low Reynolds Number Flows Via Dynamic Hybrid RANS/LES and Stochastic Modeling

Joshua Blake, Xiao Wang, Bukhari Manshoor, Shanti Bhushan, David Thompson, Adrian Sescu, Yuji Hattori

Proceedings of the 17th International Symposium on Advanced Fluid Information　190-191　2017/11
Preface (Special Issue of the Twelfth International Conference on Flow Dynamics (ICFD2015)) Peer-reviewed

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

Journal of Fluid Science and Technology　11　(4)　JFST0020-1　2016/12/28

DOI： 10.1299/jfst.2016jfst0020 　

ISSN： 1880-5558
Clustering, Enstrophy Growth and Vortex Dynamics of the High Energy (Negative Temperature) State in Quasi-Geostrophic Turbulence

N. Takahashi, K. Ishikawa, T. Miyazaki, N. Hatakeyama, Y. Hattori

Proceedings of the Thirteenth International Conference on Flow Dynamics　508-509　2016/10
Collaboration on Aeroacoustics of Low Reynolds Number Flows Via Dynamic Hybrid RANS/LES and DNS

A. Sescu, K. Walters, S. Bhushan, B. Manshoor, Y. Hattori

Proceedings of the 16th International Symposium on Advanced Fluid Information　96-97　2016/10
Direct Numerical Simulation of Compression Wave generated by High-Speed Train going through a Tunnel

K. Konno, K. Nishikawa, Y. Hattori

Proceedings of the Thirteenth International Conference on Flow Dynamics　72-73　2016/10
Direct Numerical Simulation of Formation of Wing Tip Vortices at Low Reynolds Numbers by Corrected Volume Penalization Method

K. Yoshida, Y. Hattori

Proceedings of the Thirteenth International Conference on Flow Dynamics　528-529　2016/10
Fundamental Mechanism of Fluid-Acoustic Interaction in Edge Tone

S. Iwagami, T. Kobayashi, K. Takahashi, Y. Hattori

Proceedings of the 16th International Symposium on Advanced Fluid Information　104-105　2016/10
Instability and Nonlinear Dynamics of Curved Vortices

Y. Hattori, M. Hirota, S. Dizes, T. Leweke, S. G. Llewellyn Smith, Y. Fukumoto

Proceedings of the 16th International Symposium on Advanced Fluid Information　98-99　2016/10
Numerical Analysis of Linear Instability of a Vortex Ring with Axial Flow

Y. Hattori, J. Blanco–Rodriguez, S. Le Dizes

Proceedings of the Thirteenth International Conference on Flow Dynamics　556-557　2016/10
Vortex Dynamics of the High Energy (Negative Temperature) State in Quasi-Geostrophic Turbulence

K. Ishikawa, N. Takahashi, T. Miyazaki, N. Hatakeyama, Y. Hattori

Proceedings of the 16th International Symposium on Advanced Fluid Information　106-107　2016/10
21aBU-3 Linear Stability Analysis of Two-dimensional Taylor-Green Vortices in a Stratified Flow

Suzuki S., Hattori Y., Hirota M.

Meeting Abstracts of the Physical Society of Japan　71　3011-3011　2016
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.71.1.0_3011 　

ISSN： 2189-079X
Analysis of Complex Spatiotemporal Structures of Vortices in High Reynolds Number Turbulence

T. Ishihara, Y. Hattori

Proceedings of the 15th International Symposium on Advanced Fluid Information　172-173　2015/10
Linear Stability Analysis of Two-dimensional Taylor-Green Vortices in a Stratified Fluid

S. Suzuki, M. Hirota, Y. Hattori

Proceedings of the Twelfth International Conference on Flow Dynamics　138-139　2015/10
Stability Analysis of Vortices with Axial Flow based on Energetics and Its Application

Y. Hattori, M. Hirota, Y. Fukumoto

Proceedings of the 15th International Symposium on Advanced Fluid Information　106-107　2015/10
The continuous spectrum in the Moore-Saffman-Tsai-Widnall Instability

Y. Hattori, M. Hirota, S. G. Llewellyn Smith

Proceedings of the 15th International Symposium on Advanced Fluid Information　108-109　2015/10
Vortex Dynamics of the High Energy (Negative Temperature) State in Quasi-geostrophic Turbulence

M. Ishihara, N. Takahashi, T. Miyazaki, N. Hatakeyama, Y. Hattori

Proceedings of the 15th International Symposium on Advanced Fluid Information　166-167　2015/10
統計的機械学習を用いた乱流モデルの開発

蒲原将隆, 服部裕司

京都大学数理解析研究所講究録　1944　70-77　2015/04
Publisher:
ISSN： 1880-2818
統計的機械学習を用いた新しいSGSモデルの構築に向けて

蒲原将隆, 服部裕司

日本流体力学会学会誌　33　(6)　475-477　2014/12
Publisher:
ISSN： 0286-3154
A Priori Test of Subgrid-scale Model by Machine Learning in a Turbulent Channel Flow

Masataka Gamahara, Yuji Hattori

Proceedings of the Eleventh International Conference on Flow Dynamics　118-119　2014/10
Analysis of Complex Spatiotemporal Structures of Vortices in Turbulence: Extraction of Strong Vortical Clusters in High-Reynolds-Number Turbulence

Takashi Ishihara, Yuji Hattori

Proceedings of the 14th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　172-173　2014/10
Dependence of Axial Flow inside Wing Tip Vortices on Wing Planforms

Hiroshi Koizumi, Yuji Hattori

Proceedings of the Eleventh International Conference on Flow Dynamics　74-75　2014/10
Nonlinear Evolution of Disturbed Compressible Vortex Pair

Tomohiro Ushiki, Makoto Hirota, Yuji Hattori

Proceedings of the Eleventh International Conference on Flow Dynamics　76-77　2014/10
Stability Analysis of Vortices with Axial Flow based on Energetics and its Application

Yasuhide Fukumoto, Makoto Hirota, Yuji Hattori

Proceedings of the 14th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　176-177　2014/10
The Continuous Spectrum in the Moore–Saffman–Tsai–Widnall Instability

Yuji Hattori, Makoto Hirota, Stefan G. Llewellyn Smith

Proceedings of the 14th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　178-179　2014/10
Vortex Dynamics of the High Energy (Negative Temperature) State in Quasi-Geostrophic Turbulence

Masaya Ishihara, Naoya Takahashi, Takeshi Miyazaki, Nozomu Hatakeyama, Yuji Hattori

Proceedings of the 14th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　174-175　2014/10
魚群遊泳運動の流体力学的特性の数値シミュレーション研究

矢田貝弦, 服部裕司

京都大学数理解析研究所講究録　1900　128-132　2014/06
Publisher:
ISSN： 1880-2818
弱圧縮性乱流の統計的性質と密度分布

寺門大毅, 服部裕司

京都大学数理解析研究所講究録　1882　19-30　2014/04
Publisher:
ISSN： 1880-2818
A Numerical Study of the Effect of Large Deformations of a Trailing Vortex on Its Breakdown

Naoya Takahashi, Takeshi Miyazaki, Nozomu Hatakeyama, Yuji Hattori

Proceedings of the 13th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　150-151　2013/11
Computational Study of Formation of Wing Tip Vortices at Low Reynolds Numbers

Hiroshi Koizumi, Yuji Hattori

Proceedings of the Tenth International Conference on Flow Dynamics　80-81　2013/11
Stability Analysis of Vortices with Axial Flow based on Energetics and its Application

Yasuhide Fukumoto, Yuji Hattori

Proceedings of the 13th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　168-169　2013/11
The Continuous Spectrum in the Moore-Saffman-Tsai-Windnall Instability

Yuji Hattori, Makoto Hirota, Stefan G. Llewellyn Smith

Proceedings of the 13th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　152-153　2013/11
Motion of axisymmetric magnetic eddies with swirl Peer-reviewed

Yuji Hattori, Stefan G. Llewellyn Smith

Procedia IUTAM　7　243-250　2013
Publisher: Elsevier B.V.
DOI： 10.1016/j.piutam.2013.03.028 　

ISSN： 2210-9838
4D visualization of isotropic turbulence and dynamics of high-enstrophy structures Peer-reviewed

Y. Hattori, T. Ishihara

Proceedings of JSST 2012 (International Conference on Simulation Technology)　170-174　2012/09
Volume Penalization法の誤差低減法

中野わかな, 畠山望, 服部裕司

第25回数値流体力学シンポジウム講演論文集　2011/12/21
Error Reduction for the Volume Penalization Method

W. I. Nakano, N. Hatakeyama, Y. Hattori

The eighth International Conference on Flow Dynamics Proceedings　2011/11/09
A Numerical Study of the Effect of Large Deformations of a Trailing Vortex on Its Breakdown

Naoya Takahashi, Takeshi Miyazaki, Nozomu Hatakeyama, Yuji Hattori

Proceedings of the 11th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　146-147　2011/11
Improvement of Reality of CG Motion Pictures by Hydrodynamic Effects

Takashi Ishihara, Yuji Hattori

Proceedings of the 11th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　48-49　2011/11
Initial Condition Dependency in Two-Dimensional Decaying Compressible Turbulence

Daiki Terakado, Yuji Hattori

Proceedings of the Eighth International Conference on Flow Dynamics　92-93　2011/11
New Exact Solutions for Vortex Rings with Swirl and Magnetic Field

Yuji Hattori, Stefan G. Llewellyn Smith

Proceedings of the 11th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　144-145　2011/11
The Instability of a Helical Vortex Tube with Axial Flow

Yasuhide Fukumoto, Yuji Hattori

Proceedings of the 11th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　148-149　2011/11
Differential-geometric structures of ideal magnetohydrodynamics and plasma instabilities Peer-reviewed

Y. Hattori

Journal of Math-for-Industry　3　119-123　2011/10
Publisher: Faculty of Mathematics, Kyushu University
ISSN： 1884-4774
Axisymmetric Steady Magnetic Vortices with Swirl

Stefan G. Llewellyn Smith, Y. Hattori

Proceedings of The Tenth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　144-145　2010/11
Normal-Mode Stability Analysis of a Helical Vortex Tube

Y. Fukumoto, Y. Hattori

Proceedings of The Tenth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　136-137　2010/11
Numerical Study of Formation of a Vortex Pair by Realistic Simulation Peer-reviewed

Y. Hattori, W.I. Nakano, N. Hatakeyama, Y. Fukumoto

Proceedings of the 5th International Congress on Vortex Flow and Vortex Methods　2010/11
Assessment of Volume Penalization Method for Direct Numerical Simulation of Incompressible Flows Peer-reviewed

Y. Hattori

Proceedings of The Ninth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　116-117　2009/11
Nonlinear Dynamics of Disturbed Vortices Peer-reviewed

Y. Hattori, Y. Fukumoto

Proceedings of The Sixth International Conference of Flow Dynamics　568-568　2009/11
Linear and nonlinear instability of a vortex ring Peer-reviewed

Yasuhide Fukumoto, Yuji Hattori

IUTAM SYMPOSIUM ON ELEMENTARY VORTICES AND COHERENT STRUCTURES: SIGNIFICANCE IN TURBULENCE DYNAMICS　79　283-+　2006
Shell model for rotating turbulence Peer-reviewed

Y. Hattori, R. Rubinstein, A. Ishizawa

Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics　70　(4)　6　2004

DOI： 10.1103/PhysRevE.70.046311 　

ISSN： 1063-651X
Direct simulation of acoustic sound generated by two vortex rings Peer-reviewed

O. Inoue, Y. Hattori

4th AIAA/CEAS Aeroacoustics Conference　758-764　1998
Publisher: American Institute of Aeronautics and Astronautics Inc, AIAA
DOI： 10.2514/6.1998-2329 　
Acoustic sound generated by collision of two vortex rings Peer-reviewed

O Inoue, Y Hattori

IUTAM SYMPOSIUM ON DYNAMICS OF SLENDER VORTICES　44　361-368　1998
Direct simulation of sound generated by collisions of two vortex rings Peer-reviewed

O Inoue, Y Hattori

SIXTEENTH INTERNATIONAL CONFERENCE ON NUMERICAL METHODS IN FLUID DYNAMICS　515　296-301　1998

ISSN： 0075-8450
Visualization of Shock Wave Diffraction around a 90° sharp corner

Hattori Yuji, Uchiyama Naoki, Inoue Osamu

Transactions of Visualization Society of Japan　14　(2)　39-42　1994
Publisher: The Visualization Society of Japan
DOI： 10.3154/jvs.14.Supplement2_39 　

ISSN： 0916-4731

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The result of numerical simulation of shock wave diffraction around a 90° corner is visualized by VTR animation. The two-dimensional compressible Euler equation is solved by a finite-difference scheme with high resolution. An adaptive mesh refinement algorithm is adopted to achieve high resolution. The separated shear layer developing from the diffraction edge rolls up to discrete vortices by instability. In the case of Mach number greater than 1.5, these vortices are seen to interact with the secondary shock wave; a branching phenomena of shock wave is clearly observed.

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Misc. 81

Numerical validation of suppression effect on crossflow instability by discrete roughness elements

Makoto Hirota, Yuki Ide, Takahisa Hayasida, Yuji Hattori

Nagare　38　69-72　2019/04
波のエネルギーに基づく軸流を持つ渦の安定性解析とその応用

服部裕司, 廣田真, 福本康秀

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　2015　2017
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
複雑形状物体および運動変形する物体を含む流れから発生する空力騒音の直接数値シミュレーション法の確立

服部裕司

カワイサウンド技術・音楽振興財団機関誌「サウンド」　31　15-18　2016/01
波のエネルギーに基づく軸流を持つ渦の安定性解析とその応用

服部裕司, 廣田真, 福本康秀

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　2014　2015
0814 Regression of Subgrid-scale Stress in a Turbulent Channel Flow by Machine Learning

Gamahara Masataka, Hattori Yuji

Fluids engineering conference ...　2014　"0814-1"-"0814-2"　2014/10/25
Publisher: The Japan Society of Mechanical Engineers
ISSN： 1348-0251

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The SGS mode] in LES is estimated by neural network, which is one of the methods in machine learning. Training data for learning are obtained by direct numerical simulation of turbulent channel flow with various Reynolds numbers. We use velocity gradient tensors and distance from the wall as inputs aiming at improving conventional SGS model. High correlation coefficients are obtained between SGS stress tensors by DNS and those by neural network model.
7pAN-8 Mean flow of turbulent strained vortices

Hattori Yuji

Meeting abstracts of the Physical Society of Japan　69　(2)　119-119　2014/08/22
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
28pAJ-1 Evolution of Localized Disturbances in Strained Vortices

Hattori Yuji

Meeting abstracts of the Physical Society of Japan　69　(1)　327-327　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
29pAT-9 Explosive magnetic reconnection mediated by effect of finite electron temperature

Hirota M., Hattori Y.

Meeting abstracts of the Physical Society of Japan　69　(1)　274-274　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
波のエネルギーに基づく軸流を持つ渦の安定性解析とその応用

服部裕司, 福本康秀

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
Dynamic Geometrical Analysis of High-Vorticity Regions in Isotropic Turbulence

Hattori Yuji, Ishihara Takashi

Meeting abstracts of the Physical Society of Japan　68　(2)　228-228　2013/08/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
渦構造の安定性に対する軸流効果の研究

服部裕司, 福本康秀

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
渦対の形成過程の数値解析 (オイラー方程式の数理 : カルマン渦列と非定常渦運動100年)

服部裕司, 中野わかな, 畠山望, 福本康秀

数理解析研究所講究録　1776　91-99　2012/02
Publisher: 京都大学
ISSN： 1880-2818
渦構造の安定性に対する軸流効果の研究

服部裕司, 福本康秀

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
軸流をもつらせん渦の不安定性

服部裕司, 福本康秀

理論応用力学講演会講演論文集(Web)　61st　2012
Short-wavelength stability analysis of a helical vortex tube (vol 21, 014104, 2009)

Y. Hattori, Y. Fukumoto

PHYSICS OF FLUIDS　23　(4)　2011/04

DOI： 10.1063/1.3572667 　

ISSN： 1070-6631
軸流をもつらせん渦のモード安定性解析

服部裕司, 福本康秀

日本物理学会講演概要集　66　(2)　2011

ISSN： 1342-8349
渦構造の安定性に対する軸流効果の研究

服部裕司, 福本康秀

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　2010　2011
Volume Penalization法による圧縮性流れの高精度数値シミュレーション

小松龍, 中野わかな, 服部裕司

数値流体力学シンポジウム講演論文集(CD-ROM)　25th　2011

ISSN： 2433-2674
22pEJ-11 Direct Numerical Simulation of Formation of a Vortex Pair

Hattori Y., Nakano W., Hatakeyama N.

Meeting abstracts of the Physical Society of Japan　65　(1)　339-339　2010/03/01
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Realistic Numerical Simulation of Vortex Pair Formation

Hattori Y., Nakano W. I., Hatakeyama N., Fukumoto Y.

2010　51-51　2010
Publisher: 日本流体力学会

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Formation of a vortex pair or ring from a nozzle by piston motion is regarded as one of the simplest and the most fundamental processes of vortex formation. However, in the experiments it is difficult to obtain vorticity distribution without certain amount of errors while in most of the numerical simulations the piston motion is only implicitly taken into account by imposing the inlet velocity profile. In this paper we perform a realistic direct numerical simulation of the vortex pair formation with high accuracy. The piston motion is explicitly taken into account by the volume penalization method. The two-dimensional incompressible Navier-Stokes equations are solved by the volume penalization method. For spatial differentiation the compact scheme is used for an open flow direction and the Fourier spectral method is used for the other direction. The results reveal the details of the formation process and the vorticity distribution of a vortex pair observed in the experiments. For Re=2300, L/D=1.4 the symmetric mode is close to Gaussian. The dipole and strain component are also observed.
Application of the volume penalization method to high-order accurate numerical scheme

Wakana Iwakami Nakano, Nozomu Hatakeyama, Yuji Hattori

日本流体力学会年会2010拡張要旨集　2010
A Study of Volume Penalization Method Applied to High-Order Accurate Schemes

Wakana Iwakami Nakano, Nozomu Hatakeyama, Yuji Hattori

Seventh International Conference on Flow Dynamics Proceedings　138-139　2010
楕円渦流上のKelvin波の弱非線形相互作用によって誘導される平均流 (非線形波動現象の数理と応用)

彌榮洋一, 福本康秀, 服部裕司, 廣田真

数理解析研究所講究録　1645　90-99　2009/04
Publisher: 京都大学
ISSN： 1880-2818
楕円渦流上のKelvin波によって誘導される平均流と弱非線形安定性

彌榮洋一, 福本康秀, 服部裕司

日本物理学会講演概要集　64　(1)　2009

ISSN： 1342-8349
Lagrange変位を用いた楕円渦流の弱非線形安定性

彌榮洋一, 福本康秀, 服部裕司

日本物理学会講演概要集　64　(2)　2009

ISSN： 1342-8349
楕円容器内回転流の弱非線形安定性

彌榮洋一, 福本康秀, 服部裕司

日本物理学会講演概要集　63　(1)　2008

ISSN： 1342-8349
楕円柱容器内回転流の弱非線形安定性

彌榮洋一, 福本康秀, 服部裕司

日本物理学会講演概要集　63　(2)　2008

ISSN： 1342-8349
渦輪の不安定化過程の直接数値シミュレーション:非線形領域における挙動

服部裕司, 泥谷圭亮, 福本康秀

日本物理学会講演概要集　62　(2)　2007

ISSN： 1342-8349
渦輪の不安定性の直接数値シミュレーション(共著)

九州大学応用力学研究所研究集会「乱流現象及び多自由度系の動力学，構造と統計法則」　2007
直接数値シミュレーションによる渦輪の曲率不安定性の検証(共著)

日本流体力学会年会2007講演論文集　2007
Numerical Detection of a New Instability Mode of a Vortex Ring(jointly worked)

Proceedings of FEDSM 2005, 5th Joint ASME/JSME Fluids Engineering Conference, July 30-August 2, 2007, San Diego, USA　2007
Nonlinear Evolution of a Vortex Ring(jointly worked)

EUROMECH Colloquium 491: Vortex dynamics from quantum to geophysical scales　2007
Instability of an elliptical flow: Weakly nonlinear analysis

Y. Hattori, Y. Fukumoto, K. Fujimura

WIT Transactions on the Built Environment　92　193-201　2007

DOI： 10.2495/FSI070181 　

ISSN： 1743-3509
Nonlinear Evolution of a Vortex Ring(jointly worked)

EUROMECH Colloquium 491: Vortex dynamics from quantum to geophysical scales　2007
Nonlinear evolution of disturbed vortex rings

Yuji Hattori, Yasuhide Fukumoto

ADVANCES IN TURBULENCE XI　117　310-+　2007

ISSN： 0930-8989
Numerical detection of a new instability mode of a vortex ring

Yuji Hattori, Yasuhide Fukumoto

FEDSM 2007: PROCEEDINGS OF THE 5TH JOINT AMSE/JSME FLUIDS ENGINEERING SUMMER CONFERENCE VOL 1, PTS A AND B　1111-1118　2007
細い渦輪の短波長安定性解析

服部裕司

ながれ　25　(3)　187-190　2006
Publisher: The Japan Society of Fluid Mechanics
DOI： 10.11426/nagare1982.25.187 　

ISSN： 0286-3154 2185-4912
Evolution of an Elliptical Flow in Weakly Nonlinear Regime(jointly worked)

Proc. IUTAM Symposium on Computational Physics and New Perspectives in Turbulence　433　2006
渦輪の非線形不安定性(共著)

九州大学応用力学研究所研究集会「乱流現象及び多自由度系の動力学，構造と統計法則」　2006
理想磁気渦輪のダイナミクスにおけるエネルギーバランス(共著)

第55回理論応用力学講演会　2006

DOI： 10.11345/japannctam.55.0.217.0 　
音波による燃焼制御に関する数値シミュレーション研究(共著)

第20回数値流体力学シンポジウム　2006
Evolution of an Elliptical Flow in Weakly Nonlinear Regime(jointly worked)

Proc. IUTAM Symposium on Computational Physics and New Perspectives in Turbulence　433　2006
ハイリースキュードプロペラ周り流れの数値シミュレーション -キャビテーションモデルの研究-(共著)

第20回数値流体力学シンポジウム　2006
ハイリースキュードプロペラ周り流れのシミュレーション(共著)

第19回数値流体力学シンポジウム　2005
非線形領域における渦輪の不安定性(共著)

日本流体力学会年会2005講演論文集　288　2005
Nonlinear dynamics of a disturbed vortex ring (jointly worked)

Conference on Vortex Rings and Filaments in Classical and Quantum Systems　2005
Nonlinear dynamics of a disturbed vortex ring (jointly worked)

Conference on Vortex Rings and Filaments in Classical and Quantum Systems　2005
Weakly Nonlinear Evolution of an Elliptical Flow(jointly worked)

3rd International Conference on Vortex Flows and Vortex Models　149　2005
渦輪の不安定化現象の弱非線形解析(共著)

九州大学応用力学研究所研究集会「乱流研究の異分野融合と新たな創成」　125　2005
非線形領域における渦輪の曲率不安定性(共著)

第54回理論応用力学講演会　497　2005
Weakly Nonlinear Evolution of an Elliptical Flow(jointly worked)

3rd International Conference on Vortex Flows and Vortex Models　149　2005
28pWD-9 Statistical properties of a shell model for rotating turbulence

Hattori Y., Rubinstein R., Ishizawa A.

Meeting abstracts of the Physical Society of Japan　59　(1)　298-298　2004/03/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
渦輪の曲率不安定性:局所安定性解析と弱非線形解析

服部裕司, 福本康秀

理論応用力学講演会講演論文集　53rd　2004
渦輪の不安定性：非線形性の効果(共著)

日本流体力学会年会2004講演論文集　704　2004
Instability of a vortex ring in nonlinear Regime(jointly worked)

Vortex dynamics and field interactions (Euromech 448)　2004
Magnetohydrodynamics Motion of Toroidal Mangetic Eddies(jointly worked)

21st International Congress of Theoretical and Applied Mechanics (ICTAM2004)　FM19L_11458　2004
Instability of a vortex ring in nonlinear Regime(jointly worked)

Vortex dynamics and field interactions (Euromech 448)　2004
Magnetohydrodynamics Motion of Toroidal Mangetic Eddies(jointly worked)

21st International Congress of Theoretical and Applied Mechanics (ICTAM2004)　FM19L_11458　2004
ひずみ流中の渦管の弱非線形安定性(共著)

日本流体力学会年会2004講演論文集　706　2004
ターボファンエンジン・フロントファンの新駆動方式(共著)

日本流体力学会年会2004講演論文集　432　2004
火炎と音波の相互作用の数値シミュレーション(共著)

第18回数値流体力学シンポジウム　97　2004
Short-Wavelength Stability Analysis of Vortex Rings

HATTORI Yuji, FUKUMOTO Yasuhide

2003　188-189　2003
Publisher: 日本流体力学会

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The linear stability of vortex rings are studied in the short wavelength limit. The Hill-Scrhodinger equation is modified for vortex rings and used in evaluating growth rates analytically. Two types of vortex ring are considered : Kelvin's vortex ring and a Gaussian vortex ring. The first-order instability is significant for both vortex rings as the first-order growth rate is larger than the second-order one in large intervals of ε(=ratio of the core radius to the ring radius).
Effect of curvature on paremetric resonance instability of a vortex ring

FUKUMOTO Yasuhide, HATTORI Yuji

2003　186-187　2003
Publisher: 日本流体力学会

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We investigate a global stability of Kelvin's vortex ring to three-dimensional disturbances of infinitesimal amplitude. The basic state is a steady asymptotic solution of the Euler equations in powers of the ratio ε, the core radius to the ring radius, retaining the terms to first order. The leadning-oder flow is the Rankine vortex. The effect of ring curvature makes its appearance, as the first-order perturbation to it, in the form of a dipole field, and a local straning field, a quadrupole field, follows at second order. We show that the dipole field causes a parametric resonance instability between a pair of Kelvin waves whose azimuthal wavenumbers are separated by 1. The most unstable modes occur in the short wavelength limit, under the condtraint that the radial and the azimuthal wavenumbers are of the same magnitude, and the maximum growth rate is 165/256ε. Over a wide range of ε, the dipole effect overweighs the straning field effect of O(ε^2), being well known as the Moore-Saffman-Tsai-Widnall instability. The instability mechanism is traced to stretching of disturbance vortex lines not only in the poloidal plane but also in the toroidal direction.
細い渦輪の線形安定性-局所安定性解析-(共著)

九州大学応用力学研究所研究集会「乱流研究の異分野融合と新たな創成」　151　2003
Numerical Study of Sound Scattering by a Vortex Ring(jointly worked)

Proceedings of AFI 2001　445　2001
Numerical Study of Sound Scattering by a Vortex Ring(jointly worked)

Proceedings of AFI 2001　445　2001
Linear stability of a vortex ring revisited(jointly worked)

Proceedings of the IUTAM Symposium on tubes, sheets and singularities in fluid dynamics　37　2001
Linear stability of a vortex ring revisited(jointly worked)

Proceedings of the IUTAM Symposium on tubes, sheets and singularities in fluid dynamics　37　2001
Discussion of Flow Analysis Method for Multi-Stage Cascades

KANEMOTO Toshiaki, HATTORI Yuji, TAKEDA Hideo, ITO Takahiko

Turbomachinery.　28　(1)　49-55　2000
Publisher: 日本工業出版
DOI： 10.11458/tsj1973.28.49 　

ISSN： 0385-8839 1880-2338
25aV-7 Statistical properties of Shell models for MHD turbulence

HATTORI Yuji, ISHIZAWA Akihiro

Meeting abstracts of the Physical Society of Japan　54　(2)　219-219　1999/09/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Characteristic Time Scales and Energy Transfer in MHD Turbulence(jointly worked)

Proceedings of IUTAM Symposium on Geometry and Statistics of Turbulence　89　1999
Characteristic Time Scales and Energy Transfer in MHD Turbulence(jointly worked)

Proceedings of IUTAM Symposium on Geometry and Statistics of Turbulence　89　1999
特別講演渦・衝撃波と音--直接ナビエ・ストークス・シミュレーション (「スーパーコンピューティングと計算流体科学」SCFS '98)

井上督, 服部裕司, 大沼盛

流体科学シンポジウム講演論文集　1998　1-10　1998/09
Publisher: 東北大学流体科学研究所
ISSN： 1344-2236
Direct Navier-Stokes Simulation of Sounds

INOUE Osamu, HATTORI Yuji, ONUMA Sakari

17　49-50　1998/07

ISSN： 1342-8004
Local Analysis of Decaying 2-D MHD Turbulence

ISHIZAWA Akihiro, HATTORI Yuji

16　373-374　1997/07

ISSN： 1342-8004
ヘリコプタ・ロータまわりの流れのシミュレーション (「スーパーコンピューティングと複雑系としての流体科学」SCFS '97)

服部裕司, 井上督

流体科学シンポジウム講演論文集　1997　113-118　1997/06
Publisher: 東北大学流体科学研究所
ISSN： 1344-2236
Vortex ring state and auto-rotation in helicopter-rotor flow fields

HATTORI Yuji, AKIYAMA Katsuya, INOUE Osamu

15　277-278　1996/07

ISSN： 1342-8004
Sounds Generated by Shock Wave-Vortex Interaction

INOUE Osamu, HATTORI Yuji, ONUMA Sakari

15　275-276　1996/07

ISSN： 1342-8004
28p-E-10 Local analysis of Decaying 2-D MHD Turbulence

Ishizawa A., Hattori Y.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting　1995　(4)　91-91　1995/09/12
Publisher: The Physical Society of Japan (JPS)
Wavelet analysis of Decaying 2-D MHD Turbulence

Ishizawa A., Hattori Y.

Abstracts of the meeting of the Physical Society of Japan. Annual meeting　50　(4)　74-74　1995/03/16
Publisher: The Physical Society of Japan (JPS)

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Books and Other Publications 2

C&Fortranによる数値計算プログラミング入門改訂版

服部裕司

共立出版　2009/04
C＆Fortranによる数値計算プログラミング入門

共立出版　2000

Presentations 266

ディープラーニングの流体力学研究への応用可能性 Invited

服部裕司

第37回中部CAE懇話会　2019/11/15
機械学習の乱流研究への応用可能性 Invited

服部裕司

京大数理研RIMS共同研究(公開型)「乱流基礎相似則の再検討」　2019/07/25
ニューラルネットワークによる乱流モデルの開発とその評価 Invited

服部裕司

第14 回名工大・核融合研共同セミナー　2019/07/18
Anisotropic Effects on Stability of Periodic Array of Vortices Invited

Yuji Hattori

IUTAM Symposium on Vortex dynamics in science, nature and technology　2019/06/27
Corrected Volume Penalization Method for Direct Numerical Simulation of Compressible Flow and Aeroacoustic Sound International-presentation Invited

Japan-Korea CFD workshop (JKCFD2017)　2017/11/10
Instability and Transition to Turbulence in Strained Vortices International-presentation Invited

4th International Conference on Mathematical Theory of Turbulence via Harmonic Analysis and Computational Fluid Dynamics　2015/09/24
歪んだ渦と曲がった渦の不安定性 Invited

応用数学連携フォーラム第38回ワークショップ　2013/12/04
Instability of a Helical Vortex Tube with Axial Flow International-presentation Invited

Hot Topic Workshop on Fluid Dynamics : Vortex Dynamics, Biofluids and Related Fields　2011/12/12
前向き段差による三次元境界層の横流れ不安定性制御効果の検証

廣田真, 奥山太陽, 服部裕司

第39回数値流体力学シンポジウム　2025/12/16
埋め込み境界法を用いた複雑形状周りの境界層流れの全体安定性解析

藤井陽向, 廣田真, 服部裕司

第39回数値流体力学シンポジウム　2025/12/16
Effects of turbulence on the mechanism of Ranque–Hilsch effect at low Reynolds numbers

Yuji Hattori, Taihei Yamamoto

78th Annual Meeting of the APS Division of Fluid Dynamics　2025/11/24
Mechanisms of Vortex Evolution under Acoustic Excitation in Wing-in-Ground Effect

Liangkui Tan, Yuji Hattori

78th Annual Meeting of the APS Division of Fluid Dynamics　2025/11/24
Investigation of the Growth and Breakdown of Gortler Vortices Evolving in High-Speed Boundary Layers

Adrian Sescu, Omar Es-Sahli, Zamir Koshuriyan, Yuji Hattori

78th Annual Meeting of the APS Division of Fluid Dynamics　2025/11/23
A Low-Dimensional Description of the Vortex Merger Process Driven by Hyperbolic Instability of 2D Taylor-Green Vortex

Makoto Hirota, Naoya Ueno, Yuji Hattori

78th Annual Meeting of the APS Division of Fluid Dynamics　2025/11/23
Nonlinear processes of short-wave instabilities growing in a helical vortex: saturation and turbulent transition

Daisuke Nishiyama, Yuji Hattori

78th Annual Meeting of the APS Division of Fluid Dynamics　2025/11/23
Instability and Dynamics of Vortex Rings, Helical Vortices and Hub Vortices Invited

Yuji Hattori

d'Alembert seminar, Sorbonne University　2025/10/02
Super-Resolution Reconstruction of Flow Fields Using Diffusion Model

Golsa Tabe Jamaa, Takayuki Okatani, Yuji Hattori

2025/09/19
らせん渦における楕円型不安定性の非線形発展

西山大裕, 服部裕司

日本流体力学会年会2025　2025/09/18
二次元Taylor-Green渦の双曲型不安定性が引き起こす渦合体

廣田真, 上野直哉, 服部裕司

日本流体力学会年会2025　2025/09/18
Ranque-Hilsch ヴォルテックスチューブのエネルギー分離における乱流の役割

山本泰平, 服部裕司

日本流体力学会年会2025　2025/09/18
乱流シェルモデルのモード間エネルギー輸送：ヘルムホルツ-ホッジ分解の応用

服部裕司

RIMS共同研究（公開型）「乱流と渦」　2025/07/30
Deformation and breakdown of vortex structure due to rotational-hyperbolic instability of 2D Taylor-Green vortices in rotating fluids

Naoya Ueno, Makoto Hirota, Yuji Hattori

77th Annual Meeting of the Division of Fluid Dynamics　2024/11/26
Suppression of crossflow-induced boundary layer transition on a swept wing by sinusoidal roughness elements

Makoto Hirota, Yuki Ide, Yuji Hattori

77th Annual Meeting of the Division of Fluid Dynamics　2024/11/25
Tripolar Instability of a Strained Lamb-Oseen Vortex

Aditya Sai, Pranith Ayapilla, Yuji Hattori, Stephane Le Dizes

77th Annual Meeting of the Division of Fluid Dynamics　2024/11/24
Rotational-hyperbolic instability and ring-type elliptic instability: new unstable modes of rotating stratified fluids

Yuji Hattori, Makoto Hirota

77th Annual Meeting of the Division of Fluid Dynamics　2024/11/24
Direct Numerical Simulation of the Trailing Edge Noise on a Flat Plate and the Effect of Finlets

Natsumi Hirao, Makoto Hirota, Yuji Hattori

77th Annual Meeting of the Division of Fluid Dynamics　2024/11/24
An Analysis of Self-Organization of Three Dimensional Turbulent Vortical Structure Derived from Interaction between Vortical Flow and Bundle of Vorticity Lines

Katsuyuki Nakayama, Kaito Uchima, Kazuki Sakurai, Yuji Hattori

AFI2024　2024/11/19
The Behavior of Local Geometries of Shock Wave Surfaces Propagating in Turbulent Flow

Amane Kusuhata, Kento Tanaka, Tomoaki Watanabe, Koji Nagata, Yasumasa Ito, Yuji Hattori

AFI2024　2024/11/19
Nonlinear Dynamics of Helical Vortex Disturbed by Long-Wave Instability

Yuji Hattori, Ivan Delbende, Maurice Rossi

Twenty-first International Conference on Flow Dynamics　2024/11/19
Stability of a Lamb-Oseen Vortex in a Tripolar Straining Field

Aditya Sai, Pranith Ayapilla, Yuji Hattori

Twenty-first International Conference on Flow Dynamics　2024/11/19
Effect of Wall Transpiration on Görtler Vortices in High-speed Boundary Layers

Asmaa Ahaggach, Adrian Sescu, Zamir Koshuriyan, Yuji Hattori

Twenty-first International Conference on Flow Dynamics　2024/11/19
The Mechanism of Aeroacoustic Noise Generation in Jet-Wing Interaction under the Wing-in-Ground Effect

Liangkui Tan, Yuji Hattori

Twenty-first International Conference on Flow Dynamics　2024/11/20
Analysis of Trailing Edge Noise from a Flat Plate and Effect of Finlets on the Noise using Direct Numerical Simulation

Natsumi Hirao, Makoto Hirota, Yuji Hattori

Twenty-first International Conference on Flow Dynamics　2024/11/20
On the Breakdown of Gortler Vortices into Fully-Turbulent Boundary Layer

Matthew Brockhaus, Adrian Sescu, Omar Es-Sahli, Yuji Hattori

Twenty-first International Conference on Flow Dynamics　2024/11/20
Applicability limit and time-marching algorithm of special relativistic MHD models extended by two-fluid effects

Shuntaro Yoshino, Makoto Hirota, Yuji Hattori

66th Annual Meeting of the APS Division of Plasma Physics　2024/10/08
Stability of a Lamb-Oseen Vortex in a Tripolar Strain Field

Aditya Sai, Pranith Ayapilla, Yuji Hattori

日本流体力学会年会2024　2024/09/26
回転流体中の2次元Taylor-Green渦における巨視的不安定性に起因した渦構造の変化

上野直哉, 廣田真, 服部裕司

日本流体力学会年会2024　2024/09/26
Subgrid-scale modeling of stratified turbulence using a constrained artificial neural network

Daisuke Nishiyama, Yuji Hattori

1st European Fluid Dynamics Conference　2024/09/19
Instability of helical vortices with swirl

Ivan Delbende, Maurice Rossi, Yuji Hattori, Yonghui Xu

1st European Fluid Dynamics Conference　2024/09/17
Topological change of helical vortex disturbed by long-wave instability

Yuji Hattori, Akihiro Hirano, Ivan Delbende, Maurice Rossi

1st European Fluid Dynamics Conference　2024/09/17
二流体効果によって拡張された特殊相対論的MHDモデルとその数値的可解性

吉野舜太郎, 廣田真, 服部裕司

日本物理学会第79回年次大会　2024/09/16
成層乱流のLESと機械学習による乱流モデリング

西山大裕, 服部裕司

京大数理解析研究所 RIMS共同研究, 「非平衡な乱流」　2024/07/22
波形粗さ要素の適用による後退翼面上の境界層遷移の安定化

廣田真, 井手優紀, 服部裕司

日本物理学会2024年春季大会　2024/03/19
成層乱流の機械学習による乱流モデリング

西山大裕, 服部裕司

日本物理学会2024年春季大会　2024/03/19
多孔質による空力騒音低減効果の修正VP法による直接数値シミュレーション研究

服部裕司, 中田圭亮

第37回数値流体力学シンポジウム　2023/12/16
Nonlinear Dynamics of Helical Vortex Disturbed by Long-Wave Instability Invited

Yuji Hattori

IASM-BIRS Workshop on Vortex Dynamics: the Crossroads of Mathematics, Physics and Applications　2023/12/07
Numerical investigation of wall modeling for LES using convolutional neural network

Golsa Tabe Jamaat, Yuji Hattori

76th Annual Meeting of the Division of Fluid Dynamics　2023/11/21
Nonlinear Evolution of Helical Vortex Disturbed by Long-Wave Instability

Yuji Hattori, Akihiro Hirano, Ivan Delbende, Maurice Rossi

76th Annual Meeting of the Division of Fluid Dynamics　2023/11/20
Quasi-steady state of hub vortex under multi-polar strain caused by three satellite vortices

Aditya Sai, Pranith Ayapilla, Yuji Hattori

76th Annual Meeting of the Division of Fluid Dynamics　2023/11/20
A posteriori test of convolutional-neural-network wall model for large eddy simulation

Golsa Tabe Jamaa, Yuji Hattori

日本流体力学会年会2023　2023/09/22
Quasi-Steady State of a Hub Vortex Under Multi-Polar Strain

Aditya Sai, Pranith Ayapilla, Yuji Hattori

日本流体力学会年会2023　2023/09/22
回転流体中における2次元Taylor-Green渦の不安定性の非線形発展

上野直哉, 廣田真, 服部裕司

日本流体力学会年会2023　2023/09/21
長波長不安定性によるらせん渦の崩壊過程

服部裕司, 平野晃大

日本流体力学会年会2023　2023/09/21
平板周り流れから発生する騒音の直接数値シミュレーションによる解析手法の検討

平尾菜津美, 廣田真, 服部裕司

日本流体力学会年会2023　2023/09/20
円筒管内旋回流れに生じるゆらぎとRanque-Hilsch効果の関連性

山本泰平, 服部裕司

日本物理学会第78回年次大会　2023/09/18
軸対称渦上の非線形慣性波の数値的探索とその評価

服部裕司, 阿部哲弥

日本物理学会第78回年次大会　2023/09/18
特殊相対論的プラズマの拡張MHD近似の物理的適用性とラグランジアンの探索

吉野舜太郎, 廣田真, 服部裕司

日本物理学会第78回年次大会　2023/09/18
機械学習によるLESのための乱流モデリング：SGS応力モデルと壁面モデルの開発 Invited

服部裕司

第76回LES研究会　2023/09/12
Turbulent transition of helical vortices

Yuji Hattori, Ivan Delbende, Maurice Rossi

European Turbulence Conference (ETC18)　2023/09/05
Assessment of a nonlocal data-driven approach for wall modeling in LES

Golsa Tabe Jamaat, 服部裕司

2023年度AIMR-IFS-ISM合同研究会　2023/05/10
らせん渦の不安定化過程：渦核の乱流遷移の条件

服部裕司

日本物理学会2023年春季大会　2023/03/23
特殊相対論的プラズマの拡張MHD近似の妥当性検証

吉野舜太郎, 廣田真, 服部裕司

日本物理学会2023年春季大会　2023/03/23
アジョイント法による空力騒音低減を目的とする形状最適化：形状表現の改良の効果

嶋崎渉, 服部裕司

第36回数値流体力学シンポジウム　2022/12/16
平面/凹面上における圧縮性乱流境界層の壁面温度による制御

小澤郁真, 服部裕司

第36回数値流体力学シンポジウム　2022/12/16
短波長不安定性による渦輪の乱流化過程

服部裕司

第36回数値流体力学シンポジウム　2022/12/16
らせん渦の長波長不安定性のDNSによる線形・非線形解析

平野晃大, 服部裕司

第36回数値流体力学シンポジウム　2022/12/14
Efficient evaluation of the surface roughness effect on boundary layer using quasi-statically transforming roughness shape

Takayuki Shirosaki, Makoto Hirota, Yuji Hattori

75th Annual Meeting of the Division of Fluid Dynamics　2022/11/21
A data-driven approach using CNN for wall modeling in Large Eddy Simulation

Golsa Tabe Jamaa, Yuji Hattori

75th Annual Meeting of the Division of Fluid Dynamics　2022/11/21
Turbulent transition of helical vortices destabilized by short-wave instability

Yuji Hattori

75th Annual Meeting of the Division of Fluid Dynamics　2022/11/21
Stable a posteriori LES of forced two-dimensional turbulence using shallow artificial neural networks

Aditya Sai, Pranith Ayapilla, Yuji Hattori

75th Annual Meeting of the Division of Fluid Dynamics　2022/11/20
Energy reduction of streamwise streaks in high-speed boundary layer flows via optimally controlled wall deformations

Omar ES-SAHLI, Adrian Sescu, Mohammed Z Afsar, Yuji Hattori, Makoto Hirota

75th Annual Meeting of the Division of Fluid Dynamics　2022/11/20
Laminarizing effect of nonlinearly saturated crossflow vortices sustained by a sinusoidal roughness

Makoto Hirota, Yuki Ide, Yuji Hattori

75th Annual Meeting of the Division of Fluid Dynamics　2022/11/20
Ranque-Hilsch ボルテックスチューブに生じる流れとエネルギー分離現象の関連性

山本泰平, 服部裕司

日本流体力学会年会2022　2022/09/29
平面/凹面上における圧縮性乱流境界層の直接数値シミュレーション

小澤郁真, 服部裕司

日本流体力学会年会2022　2022/09/29
人工ニューラルネットワークを使用した強制2次元乱流における LES のアプリオリ分析とアポステリオリ分析

Aditya Sai, Pranith Ayapilla, 服部裕司

日本流体力学会年会2022　2022/09/28
LES におけるチャネル乱流のデータ駆動壁面モデル

Golsa Tabe Jamaa, 服部裕司

日本流体力学会年会2022　2022/09/28
らせん渦の線形不安定性における軸流の向きの効果

服部裕司, Ivan Delbende, Maurice Rossi

日本流体力学会年会2022　2022/09/27
Instability of Curved Vortices Invited

Yuji Hattori

International Workshop on Turbulence, Vorticity Dynamics and Wind Energy　2022/09/07
空力音低減のための多孔質のマクロモデルの検証

服部裕司, 佐藤泰紀

日本物理学会第77回年次大会　2022/03/15
直接数値計算を用いたRanque-Hilschボルテックスチューブに生じる流れの研究

山本泰平, 服部裕司

日本物理学会第77回年次大会　2022/03/15
機械学習によるLES乱流モデリング

服部裕司

第37回生研TSFDシンポジウム　2022/03/04
機械学習による乱流モデリング Invited

服部裕司

講習会「流体とインフォマティクス」　2022/01/19
らせん渦の長波長不安定性の数値シミュレーション研究

平野晃大, 服部裕司

第35回数値流体力学シンポジウム　2021/12/16
軸対称渦上の非線形慣性波の特性の研究

阿部哲弥, 服部裕司

第35回数値流体力学シンポジウム　2021/12/16
動的変化する壁面粗さ形状を用いた乱流遷移抑制効果の最適化

城崎孝之, 廣田真, 服部裕司

第35回数値流体力学シンポジウム　2021/12/15
Ranque-Hilschボルテックスチューブに生じる流れの直接数値シミュレーション

山本泰平, 服部裕司

第35回数値流体力学シンポジウム　2021/12/14
二次元乱流における人工ニューラルネットワークを使用したサブグリッドスケール応力モデリング

アヤピラアヂィチャサイプラニス, 服部裕司

第35回数値流体力学シンポジウム　2021/12/14
アジョイント法を用いた空力騒音低減のための形状最適化の数値シミュレーション

嶋﨑渉, 服部裕司

第35回数値流体力学シンポジウム　2021/12/14
成層流中の渦列の安定性に対する回転の効果

服部裕司, 廣田真

日本流体力学会年会2021　2021/09/23
渦上の非線形慣性波の特性の研究

阿部哲弥, 服部裕司

日本流体力学会年会2021　2021/09/23
データ駆動型アプローチを使用したサブグリッドスケールモデリング

Golsa Tabe Jamaa, Yuji Hattori

日本流体力学会年会2021　2021/09/21
回転成層流体中の渦列の不安定性

服部裕司, 廣田真

日本物理学会2021年秋季大会　2021/09/20
Anisotropic effects on stability of periodic array of vortices Invited

服部裕司

東北大学数理科学連携研究センター・パターンダイナミクス数理セミナー　2021/05/07
波形粗さ要素による三次元境界層遷移の抑制効果

廣田真, 井手優紀, 服部裕司

日本物理学会第76回年次大会　2021/03/14
らせん渦の不安定化過程の直接数値シミュレーション研究

服部裕司, Ivan Delbence, Maurice Rossi

日本物理学会第76回年次大会　2021/03/14
多孔質材を用いた空力騒音低減のメカニズムと効果的な貼り付け手法に関する研究

佐藤泰紀, 服部裕司

第33回数値流体力学シンポジウム　2019/11/29
機械学習による空力解析手法の開発およびその検証

豊田耀山, 服部裕司

第33回数値流体力学シンポジウム　2019/11/29
Growth of nonlinear streaky structures and the associated streamwise vortices in high-speed boundary layers

Adrian Sescu, Mohammed Z. Afsar, Yuji Hattori

72nd Annual Meeting of the APS Division of Fluid Dynamics
Nonlinear dynamics of destabilized array of vortices in stratified fluid

Yuji Hattori, Makoto Hirota

72nd Annual Meeting of the APS Division of Fluid Dynamics
Development for a Theoretical Model of Crossflow-induced Boundary-layer Transition

Makoto Hirota, Yuki Ide, Takahisa Hayashida, Yuji Hattori

72nd Annual Meeting of the APS Division of Fluid Dynamics
不安定密度成層せん断流における鉛直渦度発生の数値シミュレーション

高橋翠, 廣田真, 服部裕司

日本流体力学会年会2019　2019/09/15
成層流中の渦列の不安定化過程

服部裕司, 廣田真

日本流体力学会年会2019　2019/09/15
Turbulence Modeling using Artificial Neural Network

Yuji Hattori, Satoshi Miyazaki

17th European Turbulence Conference (ETC2019)
Prediction and control of boundary-layer transition induced by steady crossflow vortices

Makoto Hirota, Yuki Ide, Yuji Hattori

IUTAM Symposium on Vortex dynamics in science, nature and technology
機械学習による空力解析手法の開発と評価

豊田耀山, 服部裕司

第65回理論応用力学講演会
DNSを用いたエッジトーンのモード遷移の再現

岩上翔, 小林泰三, 服部裕司, 高橋公也

日本物理学会第74回年次大会
成層双曲型不安定性に対する回転の効果

服部裕司, 廣田真

日本物理学会第74回年次大会
ニューラルネットワークによる乱流モデルの開発

服部裕司

Prometech Simulation Conference　2018/12
孤立粗度による横流れ不安定性抑制効果の数値的検証

廣田真, 井手優紀, 林田貴寿, 服部裕司

第32回数値流体力学シンポジウム　2018/12
ニューラルネットワークによるSGS応力のモデリングと性能評価

宮崎聡, 服部裕司

第32回数値流体力学シンポジウム　2018/12
Magneto-hyperbolic instability: a new instability due to hyperbolic instability and phase shift by Alfven waves

Yuji Hattori, Makoto Hirota, Masaru Furukawa

71th Annual Meeting of the Division of Fluid Dynamics　2018/11
Reduction of Aeroacoustic Noise Generated from a Flow past a Cylinder by Porous Materials

Yasunori Sato, Yuji Hattori

71th Annual Meeting of the Division of Fluid Dynamics　2018/11
Continued Development of a Coupled LES/Stochastic Approach to Jet Noise Prediction

Joshua Blake, Adrian Sescu, David Thompson, Yuji Hattori

71th Annual Meeting of the Division of Fluid Dynamics　2018/11
Magneto-Hyperbolic Instability: a new instability due to hyperbolic instability and phase shift by Alfven waves

Yuji Hattori

Satellite meeting of ICFD on Instability and Nonlinear Dynamics of Curved Vortices　2018/11/10
後退翼周りの境界層の遷移予測と制御に向けた直接数値解析と非線形安定性解析

廣田真, 井手優紀, 林田貴寿, 服部裕司

第56回飛行機シンポジウム　2018/11
Global Analysis of Strato-Hyperbolic Instability of Stably-Stratified Vortices

Yuji Hattori, S. Suzuki, M. Khandelwal, M. Hirota

12th European Fluid Mechanics Conference　2018/09
DNSを用いたエッジトーンの解析

岩上翔, 小林泰三, 服部裕司, 高橋公也

日本物理学会2018年秋季大会　2018/09
双曲型よどみ点をもつ渦の不安定性に対する磁場の効果

服部裕司, 廣田真, 古川勝

日本流体力学会年会2018　2018/09
統計的機械学習によるLES乱流モデルの開発

服部裕司, 宮崎聡

第50回流体力学講演会／第36回航空宇宙数値シミュレーション技術シンポジウム　2018/07
Searching for Turbulence Models for LES by Neural Network

Yuji Hattori, Satoshi Miyazaki

US-Japan Workshop on Bridging Fluid Mechanics and Data Science　2018/03/27
AC磁気ヘリシティ入射が引き起こすプラズマ周辺部のMHD挙動

廣田真, P. J. Morrison, W. Horton, 服部裕司

日本物理学会第73回年次大会　2018/03
成層双曲型不安定性の発現メカニズム

服部裕司, 鈴木翔太, Manish Khandelwal, 廣田真

日本物理学会第73回年次大会　2018/03
Jet noise prediction via coupling large eddy simulation and stochastic modeling International-presentation

174th Meeting of the Acoustical Society of America　2017/12
Numerical simulation of magnetohydrodynamic relaxation controlled by external AC loop voltages International-presentation

14th International Conference on Flow Dynamics　2017/11/03
SGS Stress Regression by Neural Network in Isotropic Homogeneous Turbulence International-presentation

The Fourteenth International Conference on Flow Dynamics　2017/11
Numerical Study of Wing Noise Reduction by Using Porous Flap International-presentation

The Fourteenth International Conference on Flow Dynamics　2017/11
Linear Instability of Compressible Vortex Pair with Axial Flow International-presentation

The Fourteenth International Conference on Flow Dynamics　2017/11
Instability and Nonlinear Dynamics of Curved Vortices International-presentation

17th International Symposium on Advanced Fluid Information　2017/11
Hyperbolic Instability of Stratified Vortices International-presentation

The Fourteenth International Conference on Flow Dynamics　2017/11
Fundamental Mechanism of Fluid-Acoustic Interaction in Edge Tone International-presentation

17th International Symposium on Advanced Fluid Information　2017/11
Aeroacoustics of Low Reynolds Number Flows Via Dynamic Hybrid RANS/LES and Stochastic Modeling International-presentation

17th International Symposium on Advanced Fluid Information　2017/11
A New Short-Wave Instability of Stratified Vortices International-presentation

70th Annual Meeting of the Division of Fluid Dynamics　2017/11
Magnetic helicity balance at Taylor relaxed states sustained by AC helicity injection International-presentation

59th Annual Meeting of the APS Division of Plasma Physics　2017/10/25
軸流をもつ渦輪の不安定化過程

日本物理学会2017年秋季大会　2017/09
エッジトーンの基礎問題の流体音響解析III

日本物理学会2017年秋季大会　2017/09
風車翼と支柱の干渉により発生する空力騒音の2次元モデルによる直接数値シミュレーション

日本流体力学会年会2017　2017/08
Direct numerical simulations of sound generated by 3D compressible flow over a circular cylinder

日本流体力学会年会2017　2017/08
Corrected volume penalization method for direct numerical simulation of compressible flow and aeroacoustic sound International-presentation

Evolution Eq. and Mathematical Fluid Dynamics　2017/07
Nonlinear Evolution of Destabilized Vortex Ring with Axial Flow International-presentation

IUTAM Symposium on Dynamics and Topology of Vorticity and Vortices　2017/06
交流電圧を用いた磁気ヘリシティ入射による定常電流駆動のシミュレーション

日本物理学会第72回年次大会　2017/03/18
軸流をもつ渦輪の不安定性：曲率不安定性と楕円型不安定性の競合

日本物理学会第72回年次大会　2017/03
エッジトーンの基礎問題の流体音響解析II

日本物理学会第72回年次大会　2017/03
渦輪の不安定化過程の直接数値シミュレーション

第30回数値流体力学シンポジウム　2016/12
Numerical study on acoustic intensity of edge tone with change of jet velocity International-presentation

172nd Meeting of the Acoustical Society of America　2016/11
Stability Criteria for Circular Vortex Tubes with Smooth Vorticity Profiles International-presentation

13th International Conference on Flow Dynamics　2016/10/12
Clustering, Enstrophy Growth and Vortex Dynamics of the High Energy (Negative Temperature) State in Quasi-Geostrophic Turbulence International-presentation

Thirteenth International Conference on Flow Dynamics　2016/10
Collaboration on Aeroacoustics of Low Reynolds Number Flows Via Dynamic Hybrid RANS/LES and DNS International-presentation

16th International Symposium on Advanced Fluid Information　2016/10
Direct Numerical Simulation of Compression Wave generated by High-Speed Train going through a Tunnel International-presentation

Thirteenth International Conference on Flow Dynamics　2016/10
Direct Numerical Simulation of Formation of Wing Tip Vortices at Low Reynolds Numbers by Corrected Volume Penalization Method International-presentation

Thirteenth International Conference on Flow Dynamics　2016/10
Effects of Density Stratification on Stability of Vortices which Possess Hyperbolic Stagnation Points International-presentation

Thirteenth International Conference on Flow Dynamics　2016/10
Fundamental Mechanism of Fluid-Acoustic Interaction in Edge Tone International-presentation

16th International Symposium on Advanced Fluid Information　2016/10
Instability and Nonlinear Dynamics of Curved Vortices International-presentation

16th International Symposium on Advanced Fluid Information　2016/10
Numerical Analysis of Linear Instability of a Vortex Ring with Axial Flow International-presentation

Thirteenth International Conference on Flow Dynamics　2016/10
Vortex Dynamics of the High Energy (Negative Temperature) State in Quasi-Geostrophic Turbulence International-presentation

16th International Symposium on Advanced Fluid Information　2016/10
Direct Numerical Simulation of Curvature Instability of a Vortex Ring International-presentation

11th European Fluid Mechanics Conference　2016/09
エッジトーンの基礎問題の流体音響解析

日本物理学会2016年秋季大会　2016/09
一様等方性乱流中の渦構造の動的統計解析

日本流体力学会年会2016　2016/09
渦輪の曲率不安定性の直接数値シミュレーション

日本流体力学会年会2016　2016/09
双曲型淀み点を持つ渦の安定性に対する密度成層効果

日本流体力学会年会2016　2016/09
Role of Vortex Reconnection in Creation of Strong Vortices International-presentation

IUTAM Symposium: Helicity Structures and Singularity in Fluid and Plasma Dynamics　2016/04
渦対における乱流ゆらぎと平均流の相互作用

日本物理学会第71回年次大会　2016/03
成層流中の2次元Taylor-Green渦の線形安定性解析

日本物理学会第71回年次大会　2016/03
埋め込み境界法による空力音直接数値解法の研究

第29回数値流体力学シンポジウム　2015/12
埋め込み境界法による振動円柱および固定円柱をすぎる流れから発生する空力音の直接数値シミュレーション

第35回流力騒音シンポジウム　2015/12
Evolution of mean flow and disturbances in strained vortices International-presentation

International Workshop on Flow Dynamics & Spintronics, 12-13 November　2015/11/12
Liner stability analysis of the two-dimensional Taylor-Green vortices in a stratified flow International-presentation

68th Annual Meeting of the APS Division of Fluid Dynamics　2015/11
Reduction of aerodynamic sound generated in a flow past an oscillating and a fixed cylinder in tandem International-presentation

68th Annual Meeting of the APS Division of Fluid Dynamics　2015/11
Analysis of Complex Spatiotemporal Structures of Vortices in High Reynolds Number Turbulence International-presentation

15th International Symposium on Advanced Fluid Information　2015/10
Linear Stability Analysis of Two-dimensional Taylor-Green Vortices in a Stratified Fluid International-presentation

Twelfth International Conference on Flow Dynamics　2015/10
Stability Analysis of Vortices with Axial Flow based on Energetics and Its Application International-presentation

15th International Symposium on Advanced Fluid Information　2015/10
The continuous spectrum in the Moore-Saffman-Tsai-Widnall Instability International-presentation

15th International Symposium on Advanced Fluid Information　2015/10
Vortex Dynamics of the High Energy (Negative Temperature) State in Quasi-geostrophic Turbulence International-presentation

15th International Symposium on Advanced Fluid Information　2015/10
一様等方性乱流中の高渦度領域の動的形状解析 II

日本物理学会2015年秋季大会　2015/09
翼端渦構造とその形成過程の数理モデル

日本流体力学会年会2015　2015/09
乱れた歪み渦における平均流変化のメカニズム

日本物理学会第70回年次大会　2015/03
ニューラルネットワークを用いたSGS応力の学習

第28回数値流体力学シンポジウム　2014/12
圧縮性流れに対するVolume Penalization法による空力音の直接数値シミュレーション

第28回数値流体力学シンポジウム　2014/12
Development of subgrid-scale model using machine learning International-presentation

67th Annual Meeting of the APS Division of Fluid Dynamics　2014/11
Evolution of mean flow and disturbances in strained vortices International-presentation

67th Annual Meeting of the APS Division of Fluid Dynamics　2014/11
Nonlinear analysis of explosive growth of collisionless magnetic reconnection in the presence of the effect of finite electron temperature International-presentation

56th Annual Meeting of the APS Division of Plasma Physics　2014/10/29
A Priori Test of Subgrid-scale Model by Machine Learning in a Turbulent Channel Flow International-presentation

the Eleventh International Conference on Flow Dynamics　2014/10
Analysis of Complex Spatiotemporal Structures of Vortices in Turbulence: Extraction of Strong Vortical Clusters in High-Reynolds-Number Turbulence International-presentation

the 14th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2014/10
Dependence of Axial Flow inside Wing Tip Vortices on Wing Planforms International-presentation

the Eleventh International Conference on Flow Dynamics　2014/10
Nonlinear Evolution of Disturbed Compressible Vortex Pair International-presentation

the Eleventh International Conference on Flow Dynamics　2014/10
Stability Analysis of Vortices with Axial Flow based on Energetics and its Application International-presentation

the 14th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2014/10
The Continuous Spectrum in the Moore–Saffman–Tsai–Widnall Instability International-presentation

the 14th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2014/10
Vortex Dynamics of the High Energy (Negative Temperature) State in Quasi-Geostrophic Turbulence International-presentation

the 14th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2014/10
統計的機械学習を用いたチャネル乱流における SGS 応力の回帰

第92期日本機械学会流体工学部門講演会　2014/10
軸流をもつ渦のパラメタ共鳴不安定性と波のエネルギー

日本流体力学会年会2014　2014/09
統計的機械学習を用いた新しいSGSモデルの構築に向けて

日本流体力学会年会2014　2014/09
翼端渦構造の翼平面形依存性の数値シミュレーション研究

日本流体力学会年会2014　2014/09
乱れた歪み渦の平均流

日本物理学会2014年秋季大会　2014/09
統計的機械学習を用いた乱流モデルの開発

京大数理解析研究所共同研究集会「乱流研究のフロンティア」　2014/07
有限電子温度効果が介在する爆発的磁気リコネクション

日本物理学会第69回年次大会　2014/03/29
歪み渦における局所擾乱の成長過程

日本物理学会第69回年次大会　2014/03
歪んだ渦における局所擾乱の成長：線形不安定性・非線形発展・乱流

平成25年度NIFS共同研究研究会「MHDおよび流体力学における流れの安定性に関する理論・シミュレーション研究」　2013/12/18
A Numerical Study of the Effect of Large Deformations of a Trailing Vortex on Its Breakdown International-presentation

13th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2013/11
Aeroacoustic sound radiated from a flow past an oscillating and a fixed cylinder in tandem International-presentation

66th Annual Meeting of the APS Division of Fluid Dynamics　2013/11
Computational Study of Formation of Wing Tip Vortices at Low Reynolds Numbers International-presentation

Tenth International Conference on Flow Dynamics　2013/11
Flow Structures and Efficiency of Swimming Fish school: Numerical Study International-presentation

66th Annual Meeting of the APS Division of Fluid Dynamics　2013/11
Stability Analysis of Vortices with Axial Flow based on Energetics and its Application International-presentation

13th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2013/11
The Continuous Spectrum in the Moore-Saffman-Tsai-Windnall Instability International-presentation

13th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2013/11
魚群遊泳運動の流体力学的特性の数値シミュレーション研究

京大数理解析研究所共同研究集会「生物流体力学における流れ構造の解析と役割」　2013/11
Dynamic Geometrical Analysis Of High-enstrophy Structures In Isotropic Turbulence International-presentation

European turbulence conference 14 (ETC14)　2013/09
Dynamic geometrical analysis of high-enstrophy structures in isotropic turbulence International-presentation

JSPS/UK Meeting on Topological Vorticity Dynamics in the Physical Sciences　2013/09
一様等方性乱流中の高渦度領域の動的形状解析

日本物理学会2013年秋季大会　2013/09
魚群遊泳運動の流体力学的特性の数値シミュレーション研究

日本流体力学会年会2013　2013/09
Evolution of localized disturbances in the elliptical flow International-presentation

IUTAM Symposium on Vortex Dynamics: Formation, Structure and Function　2013/03
Modal and non-modal stability of two-dimensional Taylor-Green vortices International-presentation

IUTAM Symposium on Vortex Dynamics: Formation, Structure and Function　2013/03
楕円型不安定性における局所擾乱の成長過程と乱流への遷移

日本物理学会第68回年次大会　2013/03
2次元弱圧縮性乱流の統計的性質と密度分布

京大数理解析研究所共同研究集会「多重物理・多重スケール乱流現象の数理」　2013/01
空力音直接数値解析のための圧縮性流れに対するVolume Penalization法の研究

第26回数値流体力学シンポジウム　2012/12
Error Analysis of Volume Penalization Method for Two-Dimensional Navier-Stokes Equations International-presentation

Ninth International Conference on Flow Dynamics　2012/09
連続型マスク関数を用いたVolume Penalization法の誤差解析

日本流体力学会年会2012　2012/09
2次元テイラー-グリーン渦のモード安定性解析

日本流体力学会年会2012　2012/09
Evolution of localized disturbances in the elliptical instability International-presentation

9th European Fluid Mechanics Conference　2012/09
A Study of Volume Penalization Method for Direct Numerical Simulation of Aeroacoustic Sound International-presentation

Ninth International Conference on Flow Dynamics　2012/09
Statistical properties and formation of sheet structures in two-dimensional decaying weakly compressible turbulence International-presentation

9th European Fluid Mechanics Conference　2012/09
Error Analysis for the Volume Penalization Method with Continuous Mask Functions International-presentation

Ninth International Conference on Flow Dynamics　2012/09
4D visualization of isotropic turbulence and dynamics of high-enstrophy structures International-presentation

International Conference on Simulation Technology (JSST2012)　2012/09
Statistical Properties of Two-Dimensional Decaying Weakly Compressible Turbulence International-presentation

Ninth International Conference on Flow Dynamics　2012/09
A Numerical Study of the Effect of Large Deformations of a Trailing Vortex on Its Breakdown International-presentation

12th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2012/09
Improvement of Reality of CG Motion Pictures by Hydrodynamic Effects: Effects of Turbulence International-presentation

12th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2012/09
Contour Dynamics of Vortex Rings with Swirl and Magnetic Field International-presentation

12th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2012/09
Modal Stability Analysis of a Helical Vortex Tube with Axial Flow International-presentation

12th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2012/09
Effects of Axial Flow on the Curvature Instability of a Helical Vortex Tube: Modal Analysis International-presentation

23rd International Congress of Theoretical and Applied Mechanics　2012/08
Motion of axisymmetric magnetic eddies with swirl International-presentation

IUTAM Symposium on Topological Fluid Dynamics　2012/07
軸流をもつらせん渦の不安定性

第61回理論応用力学講演会　2012/03
swirlをもつ磁気渦輪のcontour dynamicsとその一般化

日本物理学会第67回年次大会　2012/03
Volume Penalization法の誤差低減法

第25回数値流体力学シンポジウム　2011/12/21
Volume Penalization 法による圧縮性流れの高精度シミュレーション

第25回数値流体力学シンポジウム　2011/12
Stability of a helical vortex tube with axial flow International-presentation

APS 64th Annual DFD Meeting　2011/11/21
Error Reduction for the Volume Penalization Method International-presentation

The eighth International Conference on Flow Dynamics　2011/11/09
Development of volume penalization method for simulation of flow around complex bodies International-presentation

CCS Symposium Autumn 2011　2011/11/02
A Numerical Study of the Effect of Large Deformations of a Trailing Vortex on Its Breakdown International-presentation

11th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2011/11
Improvement of Reality of CG Motion Pictures by Hydrodynamic Effects International-presentation

11th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2011/11
Initial Condition Dependency in Two-Dimensional Decaying Compressible Turbulence International-presentation

Eighth International Conference on Flow Dynamics　2011/11
New Exact Solutions for Vortex Rings with Swirl and Magnetic Field International-presentation

11th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2011/11
The Instability of a Helical Vortex Tube with Axial Flow International-presentation

11th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2011/11
2次元弱圧縮性減衰乱流の初期条件依存性

国立天文台研究集会「天文学を中心とした理工学での乱流研究」　2011/10
軸流をもつらせん渦のモード安定性解析

日本物理学会2011年秋季大会　2011/09
軸流をもつらせん渦の短波長安定性解析

日本流体力学会年会2011　2011/09
渦対の形成過程の数値解析

ＲＩＭＳ研究集会「オイラー方程式の数理：カルマン渦列と非定常渦運動100年」　2011/07
swirlをもつ磁気渦輪のcontour dynamicsと定常進行解

日本物理学会第66回年次大会　2011/03
Axisymmetric Steady Magnetic Vortices with Swirl International-presentation

The Tenth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2010/11
Normal-Mode Stability Analysis of a Helical Vortex Tube International-presentation

The Tenth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2010/11
Numerical Study of Formation of a Vortex Pair by Realistic Simulation International-presentation

5th International Congress on Vortex Flow and Vortex Methods　2010/11
Development and Application of the Volume Penalization Method with Spectral-like Accuracy for Open Flow Conditions International-presentation

Euromech Fluid Mechanics Conference - 8　2010/09/16
Realistic DNS of Vortex Pair Formation International-presentation

The 8th Euromech Fluid Mechanics Conference　2010/09
渦対の形成過程の現実的数値シミュレーション

日本流体力学会年会2010　2010/09
渦対形成過程の直接数値シミュレーション研究

日本物理学会2010年秋季大会　2010/09
らせん渦の線形安定性解析：ノーマルモード解析と短波長解析の関係

ＲＩＭＳ研究集会「オイラー方程式の数理：力学と変分原理250年」　2010/07
機械学習と数値気象モデルを組み合わせた風速予測

統計数理研究所研究集会『乱流の統計理論とその応用』　2010/03
高精度数値解法による渦対形成過程の直接シミュレーション

日本物理学会第65回年次大会　2010/03
WRFデータと観測データによる自己学習型短時間風況予測システムの開発

第23回数値流体力学シンポジウム　2009/12
Assessment of Volume Penalization Method for Direct Numerical Simulation of Incompressible Flows International-presentation

The Ninth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration　2009/11
Local Stability Analysis of Fat Vortex Rings International-presentation

The 62nd Annual Meeting of the American Physical Society’s Division of Fluid Dynamics, Minneapolis, USA　2009/11
Nonlinear Dynamics of Disturbed Vortices International-presentation

The Sixth International Conference of Flow Dynamics　2009/11
Volume Penalization 法による渦対生成の数値解析研究

九州大学応用力学研究所共同利用研究集会「乱流現象及び非平衡系の多様性と普遍性」　2009/11
Lagrange変位による平均流の導出と弱非線形振幅方程式

日本流体力学会年会2009　2009/09
Lagrange変位を用いた楕円渦流の弱非線形安定性

日本物理学会2009年秋季大会　2009/09
渦輪の安定性：swirlの効果

日本物理学会2009年秋季大会　2009/09
Curvature instability of vortical structures International-presentation

Bifurcations and Instabilities in Fluid Dynamics, Third International Symposium, Nottingham, UK　2009/08
渦運動と音波：Hill の球形渦の場合

ＲＩＭＳ研究集会「オイラー方程式の数理：渦運動と音波１５０年」　2009/07
太い渦輪の線形安定性

日本物理学会第64回年次大会　2009/03
楕円渦流上のKelvin波によって誘導される平均流と弱非線形安定性

日本物理学会第64回年次大会　2009/03

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Research Projects 29

臨界型非線型偏微分方程式の非線型境界条件における臨界性の発見

小川卓克, 高橋太, 瀬片純市, 服部裕司, 猪奥倫左, 勝呂剛志, 中里亮介

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(A)

Institution: 早稲田大学

2025/04 - 2030/03
音声情報処理技術の応用による乱流ゆらぎの普遍法則の解明

服部裕司

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 挑戦的研究(萌芽)

Institution: 東北大学

2025/06 - 2028/03
強化学習による空力騒音低減のための最適化法の確立

服部裕司

Offer Organization: カワイサウンド技術・音楽振興財団

System: カワイサウンド技術・音楽振興財団・研究助成

Institution: 東北大学

2025/06 - 2026/05
Study of Instability and Turbulent Transition of Helical Vortices

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 - 2025/03/31
Study of Instability and Turbulent Transition of Helical Vortices

Yuji Hattori

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2021/04 - 2025/03
Creation of advanced method in mathematical analysis on nonlinear mathematical models of critical type

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)

Category: Grant-in-Aid for Scientific Research (S)

Institution: Tohoku University

2019/06 - 2024/03
Invention and explorer for undiscovered structure and principle in the mathematical analysis for the relation between fluid dynamics and combustion.

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Pioneering)

Category: Grant-in-Aid for Challenging Research (Pioneering)

Institution: Tohoku University

2017/06 - 2023/03
Study and application of the sounding mechanism of wind instruments with large-scale simulations

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Kyushu Institute of Technology

2019/04 - 2022/03
A Novel Type of Instability due to Hyperbolic Instability and Phase Shift by Waves

Hattori Yuji

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2017/04 - 2020/03

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The vortices which appear in a wide variety of flows often possess hyperbolic stagnation points. It is shown that there appears a new type of instability due to the hyperbolic instability and phase shift by waves in the vortices which possess hyperbolic stagnation points affected by density stratification, rotation, or magnetic field. The physical mechanism of this instability is revealed. Characteristics of stability including the condition of instability are also revealed. Combined effects of density stratification and rotation are elucidated. The role of the new instability in turbulent transition is clarified by numerical simulation.
Fundamental problems in sounding mechanism of wind instruments

Takahashi Kin'ya

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Kyushu Institute of Technology

2016/04 - 2020/03

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Sounding mechanisms of wind instruments was studied in two ways: aeroacoustic analysis and analysis by using delay equation models. Results of the aeroacoustic analysis are as follows. 1) By using Howe's energy corollary, the sound source of a small organ pipe was detected and the sound intensity was estimated. 2) The role of foot of a flue organ pipe was clarified. 3) The edge tone was numerically studied with DNS and mode transitions were accurately reproduced. By using a delay differential equation model, the function of the register hole was explained. The mode selection rules for multi-delay systems were studied with the linear stability analysis and their mechanisms were clarified in several situations.
Theoretical study of explosvie collapse mechanism in high-temperature plasmas by using a variational approach to multi-scale dynamical system

HIROTA Makoto, Morrison Philip J., HATTORI Yuji

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

Category: Grant-in-Aid for Young Scientists (B)

Institution: Tohoku University

2013/04 - 2016/03

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A mechanism for explosive magnetic reconnection in high-temperature plasma is investigated by analyzing the nonlinear evolution of a tearing instability in a two-fluid model that includes the effects of electron inertia and temperature. A high-resolution simulation of this model shows an explosive tendency for the nonlinear growth, where it is newly found that the explosive widening of the X-shaped current layer occurs locally around the reconnection point. The reason for the onset of this locally enhanced reconnection is explained theoretically by developing a novel nonlinear variational method. The theoretical model proves that the local reconnection can release the magnetic energy more efficiently than the global one and the estimated scaling of the explosive growth rate agrees well with the simulation results.
Non-modal stability of vortices and by-pass transition: towards general theory of hydrodynamic stability

HATTORI Yuji, FUKUMOTO Yasuhide, IWAKAMI Wakana

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2012/04 - 2015/03

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Vortices are one of the fundamental structures in various flows. The stability of vortices is the starting point in understanding the nature of the flow. Transient growth and destabilization by localized disturbances in vortices are studied theoretically and numerically in order to understand the transition to turbulence in vortical flows. In transient growth vortex stretching by straining flow is shown to be a key mechanism. Numerical results of unstable growth of localized disturbances are in good agreement with theoretical prediction. The transition to turbulence occurs after several stages of growth.
Development of Lagrangian hydrodynamics for three-dimensional nonlinear instability of vortices

FUKUMOTO Yasuhide, HATTORI Yuji

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Kyushu University

2009 - 2011

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A circular-cylindrical vortex embedded in an inviscid incompressible fluid is neutrally stable, but can be destabilized by symmetry-breaking perturbations. The Eulerian treatment has difficulty in calculating the mean flow nonlinearly induced by waves. We have developed a method of exploiting the Lagrangian variables for calculating unambiguously the mean flow, whereby all the coefficients of the amplitude equations were determined to third order in amplitude. These equations were converted into canonical Hamltonian equations by normalizing dependent variables. Besides, we investigated the short-wavelength stability by use of the WKB method, to complement the normal-mode analyses.
Nonlinear Dynamics of Curved Vortical Structures

HATTORI Yuji

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

2008 - 2011

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Vortices are important and fundamental structures in fluid dynamics. We clarify the effects of curvature on the behavior of vortices. The instability and nonlinear dynamics of a fat vortex ring, a helical vortex tube etc. are investigated theoretically ; the results are generalized to a general class of vortices which are curved. The effects of the axial flow, which exists in most of vortices, on the stability and nonlinear dynamics are also clarified by theoretical and numerical analysis. The obtained results are used to improve the statistical theory of turbulence.
Direct Numerical Simulation of Flow in Complex Geometries Competitive

2009/04 -
Mathematical studies on fluid motions under certain conditions

NAKAKI Tatsuyuki, OHMORI Katsushi, TSUJIKAWA Tohru, FUKUMOTO Yasuhide, HATTORI Yuji, SAKAJO Takashi, KIMURA Masato

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Category: Grant-in-Aid for Scientific Research (B)

Institution: Hiroshima University

2006 - 2009

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The fluid motion was studied from mathematical and numerical points of view. We focused our attention on the following cases : (1) Point vortex problems : Our studies are made under some assumptions on the strength and initial position of vortices. (2) Problems of vortex ring and so on : By the theoretical analysis, we studied the instability of vortices. (3) 1 or 2 phase-flow problems : The numerical schemes for the computer simulations were developed and studied. Our interests were the conservative schemes, and natural and effective determination of interfaces.
Three-dimensional motion of a vortex tube and quest for its optimality based on topological variational principle

FUKUMOTO Yasuhide, HATTORI Yuji

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Kyushu University

2007 - 2008
Development of Intelligent Wind Turbine Generator with Tandem Rotors: Optimization of Wind Rotor Profiles

KANEMOTO Toshiaki, HATTORI Yuji

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Kyushu Institute of Technology

2005 - 2006

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This intelligent wind turbine generator has the following peculiarities. (1) Both wind rotors start rotating at the low wind speed, but the rear wind rotor counter-rotates against the front wind rotor. (2) The increase of the wind speed makes both rotational speeds increase, and the rear wind rotor reaches the maximum rotational speed at the rated wind speed. (3) With more increment of the wind speed, the rear wind rotor decelerates gradually and begins to rotate in the same direction as the front wind rotor, and the output can be kept constant. (4) Moreover, the counter-rotation makes the output higher even if in the poor wind circumstance. To get the optimum profiles of this unit, the characteristics of the double rotational armature type doubly fed induction generator were examined in the bench tests, and the blade profiles of both wind rotors were optimized in the wind tunnel and by CFD. 1. Generator It was confirmed that the generator works well in cooperation with the tandem wind rotors and the secondary output can be got from the input circuit, namely the inner armature. 2. Optimum diameter ratio between both wind rotors The output increases with the increase of the rear wind rotor diameter, under the ratio D=(rear wind rotor diameter)/(front wind rotor diameter)=1. The rear wind rotor under D=0.84 can rotate in the same direction as the front wind rotor at the higher wind speed, but the rotor over D=0.84 can not change the rotational direction in response to the wind speed. That is, the optimum ratio is about D=0.84. 3. Optimum span between both wind rotors It is desirable to make the rear wind rotor close to the front wind rotor as possible, to get the fruitful output. 4. Flow condition around wind rotors The meridian flow velocity decreases every through the wind rotor. At the higher wind speed, the rear wind rotor comes to rotate in the same direction as the front wind rotor, and makes the flow runs upstream along the hub wall. Then, the rear wind rotor plays in place of the brake and/or pitch control which suppresses the over rotation. 5. Proposal of the optimum blade profile It is desirable that the blade profile of the front wind rotor has not the camber at the hub side for giving the sufficient wind energy to the rear wind rotor. 6. Acoustic noise The noise level of the tandem wind rotors is larger than that of the single wind rotor, and the level at the counter-rotating operation is larger than that at the rotating operation in the same direction. The noise becomes lower with the decrease of the diameter of the rear wind rotor.
Three-dimensional nonlinear stability theory of vortices from the view point of Hamiltonian dynamicalsysytems

FUKUMOTO Yasuhide, HATTORI Yuji

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: KYUSHU UNIVERSITY

2004 - 2005

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A new instability mechanism "curvature instability", originating from the curvature of vortex lines, is found for Kelvin's vortex ring. The eigenfunction is explicitly writing out and thereby asymptotic form of the growth rate at large wavelengths is derived. We have elucidated structure of the spectrum from the viewpoint of the Krein theory for Hamiltonian systems. By repeating irradiation of pulses of excimer laser on a Co-coated substrate, unstable vortex rings are created. By analyzing the micrographs of their frozen pictures. we identified four types of instability modes. We made a weakly nonlinear stability analysis of Kelvin's vortex ring. It is found from numerical analysis of the derived amplitude equations that the system exhibits a chaotic behavior. We also conducted a direct numerical simulation of a vortex ring, and clarified a detailed structure of the Widnall instability. We exploited the Hamiltonian normal form, associated with the SO(2) x O(2)-symmetry, to select possible form of the weakly nonlinear evolution equations of amplitude of the bending modes (azimuthal wavenumber m=1,-1) of Kelvin waves on an elliptically strained vortex tube. The coefficient of the amplitude equations are evaluated for non-rotating modes. The nonlinear terms make the elliptical instability saturate. However, it is pointed out that three-wave resonance of modes of m=3,4 and a bending mode derives a secondary instability. By extending Dyson's technique to three dimensions, we developed a method of asymptotic expansions of the Biot-Savart integral, which takes account of the influence of finite core thickness on a vortex tube. This method is applied to calculation of velocity field around a helical vortex tube. In the neighborhood of the core, we cannot ignore the dipoles arranged on the tube center line which reflects the distribution of vorticity in the core. A formulation of contour dynamics is given to the magnetohydrodynamic evolution of axisymmetric magnetic eddies. A family of exact solutions is found. Their significance in energy balance is clarified by both numerical implementation of the contour dynamics and a direct numerical simulation.
Numerical and mathematical analysis to low-dimensional solutions in. mathematical fluid problems

NAKAKI Tatuyuki, FUKUMOTO Yasuhide, KIMURA Masato, SUZUKI Atsushi, OHMORI Katsushi, HATTORI Yuji

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Category: Grant-in-Aid for Scientific Research (B)

2003 - 2005

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(1) We consider problems of point vortices in a plane, which are described by the two-dimensional Euler equation. (i) Stability of relative equilibria for five point vortices is treated. We found that some unstable configurations exhibit the relaxation oscillation. Four and three point vortices which exhibit the relaxation oscillation are also found. Mathematical justifications are made. (ii) When vortices come close each other, numerical difficulty occurs. To overcome this difficulty, we propose a numerical scheme. (2) We consider the point vortices in a sphere. When two vortices are fixed at the poles of sphere, the stability of some configuration and reduction to a center manifold are shown. (3) Three-dimensional linear instability of vortex flow is considered. By using spectral theory with Hamiltonian, we found a primary factor of instability for some cases. (4) To analyze the instability of vortex ring in the nonlinear region, we introduce a weakly nonlinear system by multi-scale methods. By using this system, we found the mechanism of the Windall instability and unstable modes. (5) By singular limit methods, we propose and analyze the numerical methods to the classical one-phase Stefan problems and the flow through porous media. (6) For immiscible two-phase flow, we consider a flux-free finite element method, which shows good conservation of mass. We obtain error estimates and convergence of numerical solution. (7) We apply a numerical verification method to the driven cavity problem, which is one of famous two-dimensional fluid problems. We succeeded in the verification of some steady solutions.
Development of Micro Hydraulic Turbine Applicable to Mountain Torrents and Rivers to Coexist with Natural Ecosystem

KANEMOTO Toshiaki, HATTORI Yuji

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: Kyushu Institute of Technology

2003 - 2004

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We are under obligation to coexist with natural ecosystem and to cope with warming global environment, for the next leap in hydroelectric power exploitations. In such circumstances, this research proposes a new type hydraulic turbine, named "Gyro-Type Hydraulic Turbine". The rotor is composed of some blades with high aspect ratio and the turbine is suitable for shallow stream with high velocity in mountain torrents and/or rivers. Then, the turbine scarcely disrupts the natural stream and environment, because the rotating plane of the submerged rotor is nearly parallel to the stream without casings and/or penstocks. Moreover, it is not necessary to start the public works on a large scale because the generator connected with the rotor shaft can be easily set on the simple stand over the water level. The rotor of diameter 500 mm, which is composed of three blades with NACA0018 hydrofoil, was prepared to the experiments, and the main knowledge about the turbine characteristics are as follows. (1)The turbine characteristics do not satisfy the similarity laws against the stream velocity, in this investigation. (2)The attack angle to the blade changes in the rotation because the rotating plane is moderately inclined. The output can be bettered with 20% as compared with the two dimensional blade, when the blade is twisted so as to get the best lift-drag ratio. (3)The head between upstream and downstream of the rotor is affected by not only the rotational speed, namely the output, but also the blade profile. (4)The flow pattern and the pressure around the rotating blade can be predicted well with CFD, for instance, the large circulation occurs over the blade suction surface with the large attack angle, owing to the flow separation at the leading and the trailing edges.
Stability of Vortices Competitive

2000/04 -
Higher-order asymptotic theory and numerical analysis for three-dimensional dynamics of a vortex filament in a flw

FUKUMOTO Yasuhide, HATTORI Yuji

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: KYUSHU UNIVERSITY

1999 - 2000

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1. Three-dimensional motion of a vortex filament was investigated theoretically. i) A general formula for velocity of an axisymmetric vortex ring in a viscous fluid was obtained. Numerical computation was carried through for an infinitely thin core at the initial instant. Expansion of ring radius compares well with an experimental measurement. ii) Asymptotic development of the Biot-Savart integral and matched asymptotic expansions were extended to a high order, whereby the third-order correction to the speed of a vortex tube was obtained. Its relevance to the localized induction hierarchy was discussed. 2. Three-dimensional instability of a vortex ring was calculated from the viewpoint of Hamiltonian spectrum theory. It was shown that a parametric resonance occurs between axisymmetric and bending modes due to the curvature effect. 3. Direct numerical simulations of the Navier-Stokes equations using a highly accurate finite difference scheme were performed for generation and scattering of sound waves by vortices. i) An interaction of shock waves with a vortex ring was calculated and mechanism for sound generation was clarified. ii) Pressure fluctuations of small amplitude in a far region, generated by a head-on collision of vortex rings, was successfully computed. iii) With a numerical simulation, asymptotic theories for scattering of sound by Hill's spherical vortex were assessed. iv) A numerical simulation of the Gross-Petaevskii equation was performed for sound generation in the process of reconnection of quantized vortices. 4. Using a model equation for MHD turbulence, the effect of an ordered structure in large-scale magnetic field upon scaling of characteristic time and intermittency was examined.
Sound Generation by Interactions among Vortex, Heat and Shock Wave

INOUE Osamu, HATTORI Yuuji, JU Yiguang, SASOH Akihiro, FUKUNISHI Yuu

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

1996 - 1997

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Generation mechanism and natures of sound through vortex, heat and shock wave interactions are studied both computationally and experimentally. Inoue developped a highly-accurate, compressible Navier-Stokes code (6th-order in space and 4th-order in time) and applied it to shock-vortex interauction problems. The results show that, (1) three sounds are generated successively by the interaction between a single vortex and a plane shock wave, (2) each sound has a quadrupolar nature, and (3) the strengths of the sounds depend both on the strengths of a shock wave and a vortex. Inoue also applied the code to the interaction between a pair of vortices and a shock wave, and clarified that the number of sound generated by the interaction and the characteristic naturcs of the sounds depend on whether the pair of vortices moves in the same direction as the shock wave or opposite to it. Inoue also studied compressible flowfields around a helicopter and clarified the characteristic natures of the flowfields in a vortex ring state and in an autorotation state for the first time. The results suggest strongly that the sound generation in the helicopter rotor flowfield is closely related to the interaction between the tip-vortices and the rotor baleds. Fukunishi imposed a sound wave on a turbulent boundary layr, and examined the vortical motion in the boundary layr. Fukunishi found that the turbulent boundary layr can be effectively excited by the sound wave. Sasoh studied experimentally the sound noise at the exit of a tunnel produced by a highspeed bullet train (Shinkansen), and found that attenuation of a shock wave produced by a Shinkansen is inevitable to reduce the sound noise. Sasoh proposes the use of pseudo-perforated walls in a tunnel. By using a two-dimensional Navier-Stokes code, Ju studied numerically flowfields produced by the interaction of premixed gases of H2 and air with a shock wave, and found that the so-called Richtmyer-Meshkov instability plays an important role in the generation of vortices and thus the generation of sound. Hattori simulated numerically sound pressure fields generated by the head-on collision of two vortex rings, and found the following important results. (1) When the strengths of the two vortex rings are equal, two sounds are generated and each sound has quadrupolar nature. (2) When the strengths of the two vortex rings are not equal, four sounds are generated and the direction of the sound propagation is affected by the difference of the strengths of the two vortex rings. Hattori and lnoue also studied the characteristic natures of sound generated by oblique collisions of two vortex rings, and captured numerically the generation of octupolar sounds.
一様圧縮性乱流のモデリングと高精度大規模数値計算による研究

服部裕司

Offer Organization: 日本学術振興会

System: 科学研究費助成事業奨励研究(A)

Category: 奨励研究(A)

Institution: 東北大学

1995 - 1995

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第一に、圧縮性乱流における素過程として重要である渦と衝撃波の相互作用について高精度直接数値計算コードの開発と数値解析を行なった。渦と衝撃波の強さに応じて衝撃波の正常反射及びマッハ反射に相当する現象が見られることを確認し、相互作用により発生する音波の生成メカニズムを解明し、これより音波の極性を説明することに成功した。圧縮性乱流中では渦の非線形相互作用による乱流騒音が発生する。乱流騒音の数値的研究へのステップとして、渦輪の衝突に伴って発生する空力音の高精度直接数値計算コードの開発と数値解析を行なった。渦輪の正面衝突の場合について、大気圧に比べて微小な音圧を精度良く捉えることができ、実験結果とも良く一致することを確認した。特に、音波が単極音成分と四重極音成分に分解されることが非常に高い精度で示された。また、実験では困難である空力音理論との定量的比較を行ない、空力音理論の精度を検証した。その結果、本来低マッハ数における近似理論である漸近接続展開による理論が、ある程度高いマッハ数においても正しいことがわかった。さらに、空力音の発生機構を、渦に備わっている音源の非定常運動の立場から説明できることを示した。渦輪の斜め衝突の場合についても計算を行ない、渦輪の切りつなぎに関連して単極音成分、四重極音成分に加えて八重極音成分が大きく現れることを確認した。乱流燃焼については、予混合火炎の乱流燃焼速度の圧力依存性について、最新の興味深い実験結果との比較解析を行なうため、スペクトル法による大規模直接数値計算コードを開発した。コードの検証を終え、現在数値計算と解析を行なっている。
音波と火炎の相互作用 Competitive
Sound-Flame Interaction Competitive
Motion of Magnetic Eddies Competitive
電磁流体渦の運動 Competitive

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Works 8

Nonlinear Dynamics of Curved Vortical Structures

2008 - 2012
曲がりをもつ渦構造の非線形ダイナミクス

2008 - 2012
トポロジー的変分原理による渦管の3次元運動とその最適性の追求

2007 - 2010
特殊な挙動をする流体の数理的研究

2006 - 2009
タンデムロータ型インテリジェント風力発電機の研究開発:風車ロータの好適化

2005 - 2007
ハミルトン力学系的視点に立つ渦の３次元非線形安定性理論

2004 - 2006
数理流体問題における低次元的な解の数値解析と数学解析

2003 - 2006
回転乱流における要素渦構造の理論研究とその乱流モデルへの応用

2001 - 2002

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Social Activities 3

九州工業大学理数教育支援センター10周年記念フォーラム

2015/10/03 -

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九州工業大学理数教育支援センター10周年記念フォーラム―地域と協働する理数教育―のパネルディスカッションにおいてパネリストを務めた。
北九州地域産業人材育成フォーラム青少年育成プログラムアドバイザー

2013/05/24 -

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小中高生の社会体験・理数教育支援を行う上記プログラムにおいてアドバイザーを務めた．
九州工業大学研修会「竜巻ってなぁに？」

2012/02/03 -

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研修会において「ジュニア・サイエンス・スクール～気象～やり方の再現」の題目で招待講演を行った。

Other 2

複雑形状物体および運動変形する物体を含む流れから発生する空力騒音の直接数値シミュレーション法の確立

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回転翼をもつ機器に代表される複雑形状物体および運動変形する物体を含む流れから発生する空力騒音の直接数値シミュレーション法を確立することが本研究の目的である。回転する翼をもつ機器は、家庭用の扇風機、パソコン用のファンからヘリコプターや風車まで幅広く存在する。これらの機器の多くは騒音を発生する。機器の高機能化・高速化に伴って騒音が増大するのに対し、生活環境の静粛化の要求レベルは上がり、騒音低減は重要な課題である。これらの機器の騒音のうち、空気の流れと回転翼や機器本体の干渉による空力騒音が大きな比率を占める。空力騒音低減のためには、騒音発生のメカニズムを正確に捉える技術が必要である。本研究は実験観測に比べて精度とコストの面で有利な数値シミュレーション法によりその技術を確立するものである。
渦の不安定性の理論解析と数値解析

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渦の不安定性の理論解析と数値解析