Multi-scale analysis of subgrid stress and energy dissipation in turbulent channel flow

In present study, the subgrid scale (SGS) stress and dissipation for multiscale formulation of large eddy simulation are analyzed using the data of turbulent channel flow at Re _τ  = 180 obtained by direct numerical simulation. It is found that the small scale SGS stress is much smaller than the large scale SGS stress for all the stress components. The dominant contributor to large scale SGS stress is the cross stress between small scale and subgrid scale motions, while the cross stress between large scale and subgrid scale motions make major contributions to small scale SGS stress. The energy transfer from resolved large scales to subgrid scales is mainly caused by SGS Reynolds stress, while that between resolved small scales and subgrid scales are mainly due to the cross stress. The multiscale formulation of SGS models are evaluated a priori, and it is found that the small–small model is superior to other variants in terms of SGS dissipation.