Details of the Researcher

PHOTO

Hirotaka Maeyama
Section
Graduate School of Engineering
Job title
Specially Appointed Assistant Professor(Research)
Degree

Research History 1

  • 2021/04 - Present
    Tohoku University　Graduate School of Engineering

Professional Memberships 1

  • 日本航空宇宙学会

Research Interests 2

  • 数値流体力学

  • 航空宇宙工学

Research Areas 2

  • Aerospace, marine, and maritime Engineering / Aerospace engineering /

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

Papers 4

  1. Near-wall numerical coherent structures and turbulence generation in wall-modelled large-eddy simulation Peer-reviewed

    Hirotaka Maeyama, Soshi Kawai

    Journal of Fluid Mechanics　969　2023/08

    Publisher: Cambridge University Press (CUP)

    DOI： 10.1017/jfm.2023.575 　

    ISSN： 0022-1120

    eISSN： 1469-7645

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    Near-wall turbulence structures and generation in the wall-modelled large-eddy simulation (WMLES) are revealed. To elucidate the turbulence structures driving a near-wall turbulence generation in the WMLES, flat-plate turbulent boundary-layer flows calculated by the WMLES and direct numerical simulation (DNS) are closely investigated. A conditional-averaging technique is applied to the instantaneous flow fields and the near-wall statistical structures of the ejection and sweep pairs, which produce the turbulence, are revealed to exist even in the WMLES although the structures are non-physically elongated compared with those obtained by the DNS. Since the near-wall turbulence structures in the WMLES are revealed not to be disordered, but to be coherent structures with low- and high-speed fluids alternating in the spanwise direction, it is suggested that the near-wall turbulence generation in the WMLES is explained by the numerically elongated coherent structures. Furthermore, the Reynolds number effects of wall-bounded turbulent flows, i.e. the appearance of the outer peak in the energy spectrum of the streamwise velocity fluctuations at increasing Reynolds numbers, is found not to be reproduced by the WMLES, and the origin of the outer peak is discussed in association with the inner–outer-layer interactions. The near-wall turbulence structures in the WMLES could depend heavily on the computational grids and the numerical methods. Therefore, additional cases varying the grid resolutions and the numerical methods (numerical schemes and sub-grid-scale models) are also conducted to confirm the consistency of the present conclusions.

  2. Unsteady aerodynamic simulations by the lattice Boltzmann method with near-wall modeling on hierarchical Cartesian grids Peer-reviewed

    Hirotaka Maeyama, Taro Imamura, Jun Osaka, Naoki Kurimoto

    Computers & Fluids　233　2022/01

    DOI： 10.1016/j.compfluid.2021.105249 　

    ISSN： 0045-7930

    eISSN： 1879-0747

  3. Turbulent channel flow simulations using the lattice Boltzmann method with near-wall modeling on a non-body-fitted Cartesian grid Peer-reviewed

    Hirotaka Maeyama, Taro Imamura, Jun Osaka, Naoki Kurimoto

    Computers & Mathematics with Applications　93　20-31　2021/07

    DOI： 10.1016/j.camwa.2021.04.003 　

  4. Application of wall-modeled large-eddy simulation based on lattice boltzmann method to external flow analyses

    Hirotaka Maeyama, Taro Imamura, Jun Osaka, Naoki Kurimoto

    AIAA Scitech 2021 Forum　1-20　2021

    Publisher: American Institute of Aeronautics and Astronautics Inc, AIAA

Research Projects 2

  1. 乱流構造に基づく高レイノルズ数乱流境界層の壁面近傍モデリング

    前山 大貴

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 若手研究

    Institution: 東北大学

    2022/04/01 - 2024/03/31

  2. 格子ボルツマン法に基づく航空機周り高レイノルズ数流れの数値空力音響解析

    前山 大貴

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 特別研究員奨励費

    Institution: 東京大学

    2019/04/25 - 2021/03/31

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    本年度は，格子ボルツマン法(lattice Boltzmann method; LBM)を用いた高レイノルズ数壁乱流解析を，実用的な計算コストで実現可能にするLES (large-eddy simulation) 壁面近傍モデリングの開発及び，その検証計算を実施した．現在の計算機性能で，航空機周りのような高レイノルズ数流れをLESで解析するためには，乱流境界層内層域における乱流ダイナミクスをモデル化する壁面近傍モデリングの使用が必須である．一方で，LBMは直交格子法に基づく数値流体解析手法であるため，任意形状周りの解析を行う際には計算格子の格子線と物体境界が一致しない物体非適合格子上での解析が必要となる．本研究では，物体非適合格子状でも高精度に高レイノルズ数壁乱流を解析できるように，既存のLES壁面近傍モデリングをさらに発展させた．また提案手法の解析精度を検証するため，格子線と壁面境界が一致する物体適合格子と，一致しない物体非適合格子の両方のケースにおけるチャネル乱流の解析を実施した．その結果，提案手法では，物体非適合格子のケースにおいても，平均速度やレイノルズせん断応力といった乱流境界層のプロファイルが再現できることが確認された．また提案手法の応用計算として，タンデム円柱及び航空機高揚力装置(30P30N)周りの非定常流れ場解析を実施した．タンデム円柱周りの流れ場解析では，円柱表面の圧力係数やパワースペクトル密度などについて，実験結果の傾向が再現されることが確認された．30P30N周りの流れ場解析では，航空機の実形状に近い比較的複雑な形状周りの流れ場であっても本提案手法で解析可能であることを実証し，また表面圧力のパワースペクトル密度について，格子を細かくするほど実験結果に近づく傾向にあることが確認された．