Effect of subgrid models on the computed interscale energy transfer in isotropic turbulence

Direct and large eddy simulations of forced and decaying isotropic turbulence have been performed to investigate the behavior of subgrid models. Various subgrid models have been analyzed (i.e. Smagorinsky's eddy viscosity model, dynamic eddy viscosity model, dynamic one-equation model for the subgrid kinetic energy and scale-similarity model). A priori analysis showed that the subgrid stress and the subgrid energy flux predicted by the scale similarity model, and subgrid kinetic energy model (with fixed coefficients) correlate reasonably well with exact data, while the Smagorinsky's eddy viscosity model showed relatively poor agreement. However, the correlation for the scale similarity model decreased much more rapidly with decrease in grid resolution when compared to the subgrid kinetic energy model. The subgrid models were then used to carry out large-eddy simulations for a range of Reynolds number. When dynamic evaluation was incorporated, the correlation improved significantly. The dynamic subgrid kinetic energy model showed, consistently, a higher correlation for a range of Reynolds number when compared to the dynamic eddy viscosity model. These results demonstrate the capabilities of the dynamic one-equation model.