| Project/Area Number |
18K13689
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 19010:Fluid engineering-related
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| Research Institution | Osaka University |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2019: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2018: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
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| Keywords | 壁乱流 / 乱流モデル / LES / 不変解 / 壁面モデル / 一様せん断乱流 / クエット流 / 乱流 / スケーリング / Large Eddy Simulation / 非線形 / ラージエディシミュレーション |
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| Outline of Final Research Achievements |
The invariant solutions in the large-eddy simulation (LES), i.e., filtered Navier-Stokes equation, are investigated for the development of a high-fidelity turbulence model. The invariant solutions in uniform shear flow are traced along with the parameters, and new periodic orbits are obtained. These invariant solutions give us the theoretical background for the self-sustaining turbulence with eddy viscosity and the similarity with the self-sustaining motions of wall-bounded shear turbulence in the Navier-Stokes (NS) equation. The relatively high-Reynolds-number equilibrium in a plane Couette flow in NS equation is obtained, and the wall-bounded solutions resemble invariant solutions in the LES equation, which paves a way of developing a wall model for eddy viscosity.
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| Academic Significance and Societal Importance of the Research Achievements |
Navier-Stokes方程式を時間発展させる直接数値計算(DNS)は膨大な計算時間がかかるため，設計の試行錯誤の為には，乱流モデルを適用して計算コストを減らすことが必要不可欠である．乱流の大スケール運動のみを計算し，小スケール運動はモデル化するラージ・エディ・シミュレーション（LES)という手法の高速化・高精度化は流体工学において重要な課題であり，格子に依存せず，局所的に乱流と層流が混在する剥離流れなどにも適用可能な普遍的なモデルの構築が必要である．DNSの壁乱流の厳密解とLESの不変解を比較検討することで，LESの壁面モデルの開発指針への重要な知見となる．
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