The Effect of Reynolds Number in Compressible Channel Flow

Abstract

In this paper, the direct numerical simulation is applied to investigate the compressible channel flow with Re=3000, 6800, 10800, 21000 and Mach number Ma=0.8.The Reynolds number effect on the statistical characteristics of the turbulence in a compressible channel is studied, as well. It is found that the high Reynolds number effect in incompressible flow also exists in compressible flow when the Reynolds number increases to Re=21000 (Reτ=1040), but some statistical results need to be corrected when Ma=0.8. For example, the Von Kamen number in the Logarithm Law in the turbulent boundary layer is suggested to be modified to 0.417 when Ma=0.8. Unlike the term of generation of turbulent kinetic energy is balanced with the term of dissipation in incompressible turbulence, the generation term of the turbulent kinetic energy in the logarithmic region of a compressible turbulence is approximately 1.2 times than that of the dissipation term. The phenomenon of "scale separation" in incompressible turbulence also exists in the compressible turbulent boundary layer, but the location of large scale in the outer region is farther from the wall and the length of streamwise scale is shorter in the pre-multiplied power spectra of the streamwise velocity fluctuation.