EVALUATION OF THE DYNAMIC SUBGRID-SCALE STRESS MODEL IN FINITE-DIFFERENCED LES: EFFECTS OF GRID RESOLUTION AND INHOMOGENEOUS TEST FILTERING

摘要

The dynamic subgrid-scale stress model (Germano et al., 1991) is used for the Large Eddy Simulations of the turbulent channel flow at Re{sub}τ = 1050. Finite difference approximations based on the Harlow -Welch scheme are used to discretize the governing flow equations. The test filter is based on a second-order trapezoidal rale. The effects of model predictions for different grid resolutions and the application of the test filter in the wall normal inhomogeneous direction are investigated. The grid resolution study showed that the dynamic model responds in a manner consistent with the physics. The results obtained are in good agreement with experiments as well as spectral LES (Piomelli, 1993) performed at the same Reynolds number. It is found that the application of the test filter in the inhomogeneous wall normal direction has a small effect on the dynamic constant and the turbulence statistics. In general the dynamic constant decreases making the model less dissipative.