Mixed scale model expanded to subgrid diffusivity

In the large-eddy simulation frame for non-isothermal turbulent flow, the M ixed Scale Model is extended to the subgrid diffusivity, in order to dissoc iate the computation of subgrid viscosity and diffusivity. The identificati on of the subgrid thermal dissipation term in the subgrid flux transport eq uation leads to an algebraic expression of the subgrid diffusivity. This di ffusive model, as the Smagorinsky one, is weighted by a model based on scal e similarity. This expression leads to satisfactory results when applied to a buoyant turbulent pow in a differentially heated cavity. (C) 2000 Academ ie des sciences/Editions scientifiques et medicales Elsevier SAS.