Abstract
A statistical theory for compressible turbulent shear flows subject to buoyancy effects is developed. Important correlation functions in compressible shear flows are calculated with the aid of a multiscale direct-interaction approximation. They are expressed in the gradient-diffusion form similar to the eddy-viscosity representation for the Reynolds stress in incompressible flows. The results obtained are applicable to subgrid modeling, and a Smagorinsky-type model in compressible flows is constructed.