COMPRESSIBILITY EFFECTS ON THE GROWTH AND STRUCTURE OF HOMOGENEOUS TURBULENT SHEAR-FLOW

Compressibility effects within decaying isotropic turbulence and homog eneous turbulent shear flow have been studied using direct numerical s imulation. The objective of this work is to increase our understanding of compressible turbulence and to aid the development of turbulence m odels for compressible flows. The numerical simulations of compressibl e isotropic turbulence show that compressibility effects are highly de pendent on the initial conditions. The shear flow simulations, on the other hand, show that measures of compressibility evolve to become ind ependent of their initial values and are parameterized by the root mea n square Mach number. The growth rate of the turbulence in compressibl e homogeneous shear flow is reduced compared to that in the incompress ible case. The reduced growth rate is the result of an increase in the dissipation rate and energy transfer to internal energy by the pressu re-dilatation correlation. Examination of the structure of compressibl e homogeneous shear flow reveals the presence of eddy shocklets, which are important for the increased dissipation rate of compressible turb ulence.