Study of the large-eddy simulation subgrid terms of a low Mach number anisothermal channel flow

Abstract

The subgrid terms of the low Mach number equations are investigated in a strongly anisothermal low Mach number flow. The filtered low Mach number equations are established in three formulations in order to compare the unweighted classical filter and the density-weighted Favre filter on the one hand, and the filtering of the momentum conservation equation and the velocity transport equation on the other hand. In the three formulations, we establish the filtered equations of mass conservation, momentum conservation, energy conservation, of the ideal gas law and of the resolved kinetic energy transport equation. The magnitude of all subgrid terms is assessed a priori in the three formulations using the results of direct numerical simulations of a strongly anisothermal fully developed turbulent channel flow. The classification of the subgrid terms gives the relevance of various effects of the temperature gradient.