An Investigation of SGS Stress Anisotropy Modeling in Complex Turbulent Flow Fields

An anisotropy-resolving subgrid-scale (SGS) model for large eddy simulation was investigated. Primary attention was given to the predictive performance of the SGS model in the case of complex turbulence with flow impingement and/or flow separation. The SGS model was constructed by combining an isotropic linear eddy-viscosity model with an extra anisotropic term. Since the extra anisotropic term was modeled to prevent undesirable energy transfer between the grid-scale and SGS parts, the model is expected not to seriously affect computational stability. To validate the model performance for complex turbulent flow fields, the SGS model was applied to numerical simulations of a plane impinging jet and 3-D diffuser flow as well as fundamental plane channel flows. The SGS model provided reasonable predictions for these test cases. Furthermore, the predicted SGS stress components were decomposed into linear and anisotropic parts and their roles were investigated in detail. The usefulness of the present anisotropy-resolving SGS model in practical engineering applications was thus described.