HYPERVISCOSITY AND VORTICITY-BASED MODELS FOR SUBGRID SCALE MODELING

Large-eddy simulations corresponding to the decaying isotropic turbule nce experiment of Comte-Bellot and Corrsin are performed, using a pseu do-spectral code that incorporates four models: viscosity and hypervis cosity types, each implemented for both the subgrid scale stress tenso r and the subgrid scale force. Two 1/T scalings are also considered fo r the viscosity amplitude. The dynamic procedure is extended to the fo ur models and is tested. Results are obtained with and without this pr ocedure and for both scalings. The main conclusions are: (a) the two v iscosity models perform equally well; (b) the Kolmogorov scaling perfo rms as well as the Smagorinsky scaling, yet it is computationally more efficient; (c) in the dynamic procedure, there is a fairly wide range of test to grid filter ratios which produces results insensitive to t his ratio; and (d) the hyperviscosity models lead to energy decay curv es that follow the experimental data as well as the usual viscosity mo dels.