摘要

Turbulent compressibility effects are discussed with the aid of the turbulence theory based on the mass-weighted averaging. They are classified into two groups: one is the effect through the compressible part of velocity fluctuation, and the other is the direct effect of density fluctuation. In this work, attention is focused on the former, and the Reynolds stress is modeled on the basis of a nonequilibrium turbulent-viscosity representation dependent on the Lagrange derivative of turbulence quantities. Supersonic effects occur, besides the mean-density variation, in the combination of nonequilibrium and turbulent Mach-number effects. This model may reproduce the reduction in the growth rate of a free-shear layer flow, without causing wrong supersonic effects on wall-bounded flows such as channel and boundary layer flows.