スケール相似則モデルの併用によるダイナミックSGSモデルのチャネル乱流LESによる検証

概要

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The drawbacks of the dynamic sub-grid scale eddy viscosity model proposed by Germano et al. in 1991 are that homogeneous direction of turbulence is required to eliminate numerical instability due to negative eddy viscosity and that the model is unable to predict sub-grid scale turbulent energy backscattering from sub-grid scale to grid scale. In the present study, the localized dynamic sub-grid scale model proposed by Meneveau et al. in 1994 was utilized with the mixed sub-grid scale model proposed by Vreman et al. in 1994 to eliminate these shortcomings. A newly developed eddy viscosity type sub-grid scale model was used instead of Smagorinsky's model which does not require the local equilibrium state of SGS energy. The proposed model was tested by simulating turbulent channel flow at Re=180 normalized by channel-half width and friction velocity. The results showed good agreement with direct numerical simulation data obtained by Kim et al. Relationships between the turbulent coherent structures and the Grid scale turbulent energy dissipation by the SGS model were also investigated. Some advantages of using the scale similarity model to simulate turbulent coherent structures were pointed out.
1996-09-25