Analysis and modeling of spatial and temporal non-local properties of turbulent eddy diffusivity approximation

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04282
• 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: The University of Tokyo
• Principal Investigator: Hamba Fujihiro 東京大学, 生産技術研究所, 教授 (20251473)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 乱流モデル / 渦拡散率 / 非局所性

Outline of Final Research Achievements

Non-local properties of scalar flux were analyzed using numerical simulation and a model of the non-local eddy diffusivity was proposed using turbulence theory to improve the eddy diffusivity model for scalar transport. Direct numerical simulation of homogeneous isotropic turbulence with inhomogeneous mean scalar was performed to clarify spatial and temporal non-local effects of the mean scalar gradient on the turbulent scalar flux. A form of the non-local eddy diffusivity expressed by two-point velocity correlation was obtained using turbulence statistical theory and was validated using numerical data.

Free Research Field

流体物理学

Academic Significance and Societal Importance of the Research Achievements

乱流輸送の非局所性は大気境界層などの気象分野では着目されてきたが、多くの分野の実用的な乱流計算では簡単のため局所的なモデルが用いられてきた。近年機械学習などの大量のデータを用いたモデル手法の進展にともない、乱流の非局所的なモデル化が再認識されている。単に経験的なモデルを立てるのではなく、乱流統計理論の知見を生かし系統的なモデルを導出し数値計算で実証することは、乱流研究の進展に対して重要な役割を果たす。