The world's largest Direct Numerical Simulation of turbulent channel flows and its application of modeling

• Project/Area Number: 18K03923
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: University of Yamanashi
• Principal Investigator: YAMAMOTO Yoshinobu 山梨大学, 大学院総合研究部, 准教授 (40377809)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2020: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2019: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000); Fiscal Year 2018: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
• Keywords: 高レイノルズ数効果 / 壁面乱流場 / 直接数値計算 / DNSデータベース / 乱流理論 / 乱流モデリング / 高レイノルズ数 / 壁面乱流 / 乱流エネルギ / 乱流散逸率 / 乱流統計量 / 乱流モデル / 乱流輸送現象 / 散逸率

Outline of Final Research Achievements

The high-resolution Direct Numerical Simulation (DNS) database of a fully-developed channel flow up to the friction Reynolds number 8000 are established by means of a hybrid Fourier-spectral method in the wall-parallel directions and a second-order accurate finite-difference method in the wall-normal direction. Turbulent kinetic energy production rate is exceeded to the turbulent dissipation rate at the logarithmic regions in the mean velocity profiles in all Reynolds number range. However, remarkable isotropic tendency of the turbulent dissipation rate is confirmed.
Furthermore, we succeeded to the develop the world’s fastest DNS (Direct Numerical Simulation) code for the world’s largest friction Reynolds number 16000 on Super Computer Fugaku at RIKEN.

Academic Significance and Societal Importance of the Research Achievements

工学的に重要な壁面に沿って流れる乱流場（壁面乱流場）における高レイノルズ数効果の解明において重要となる直接数値計算(DNS)データベースの構築に成功した。対象とするレイノルズ数条件は摩擦速度に基づくレイノルズ数（Re_tau）で8000に達し、現時点で世界最大レイノルズ数条件に相当する。本DNSデータベースを解析することにより乱流モデリングや乱流制御に必要な高レイノルズ数乱流理論の検証が促進されることが期待できる。
さらに理化学研究所の富岳上における数百万並列規模のDNSコード開発に成功し、世界最速の演算速度を確認し、Re_tau=16000規模への拡張を可能とした。

Research Products

• [Int'l Joint Research] メルボルン大学(オーストラリア)
• [Int'l Joint Research] The University of Melbourne(オーストラリア)
• [Journal Article] Linear response theory for one-point statistics in the inertial sublayer of wall bounded turbulence (2019)
  • Author(s): Y. Kaneda, Y. Yamamoto, and Y. Tsuji
  • Journal Title: Physical Review Letters Volume: 122 Issue: 19 Pages: 194502-194502
  • DOI: 10.1103/physrevlett.122.194502
  • NAID: 120006723415
  • Peer Reviewed / Open Access
• [Journal Article] Pressure and spanwise velocity fluctuations in turbulent channel flows: Logarithmic behavior of moments and coherent structures (2019)
  • Author(s): A. Mehrez, J. Philip, Y. Yamamoto, and Y. Tsuji
  • Journal Title: Physical Review Fluids Volume: 4 Issue: 4 Pages: 044601-044601
  • DOI: 10.1103/physrevfluids.4.044601
  • NAID: 120006650160
  • Peer Reviewed / Int'l Joint Research
• [Presentation] REYNOLDS NUMBER EFFECT OF TURBULENT DISSIPATION RATE IN A FULLY-DEVELOPED CHANNEL FLOW (2019)
  • Author(s): Y. Yamamoto and Y. Tsuji
  • Organizer: 11th International Symposium on Turbulence and Shear Flow Phenomena
  • Int'l Joint Research
• [Presentation] Discussion on High-Reynolds Number Limit in a Fully-Developed Channel Flow (2018)
  • Author(s): Y. Yamamoto and Y. Tsuji
  • Organizer: Fifteenth International Conference on Flow Dynamics
  • Int'l Joint Research / Invited
• [Remarks] DNSデータベース
  • URL: http://www.me.yamanashi.ac.jp/lab/yamamoto/DNS2.html
• [Remarks] DNSデータベース
  • URL: http://www.me.yamanashi.ac.jp/lab/yamamoto/DNS2
• [Remarks] DNS database of turbulent channel flow
  • URL: http://www.me.yamanashi.ac.jp/lab/yamamoto/DNS2