Numerical studies of scaling exponents in compressible wall-bounded turbulence

Compressible turbulent channel flows at two Mach numbers (M = 0.8 and 1.3) are simulated by the numerical integration of the Navier-Stokes equations with a high-order compact finite difference scheme. The comparative studies of incompressible and compressible flows indicate that the effect of compressibility on the scaling exponents is small in the region near y+ = 20 and in the center while it is significant in the viscous sublayer (y+ =5.5) and the log-law region (y+ [asymptotically equal to] 120) . Further studies on the variation of the relative scaling exponent show that the channel can be divided into four distinct zones according to their scaling behavior: viscous sublayer and lower edge of buffer layer (I); the outer part of the buffer layer and lower part of log region (II); the major part of the log region and lower edge of the center region (M); and finally the other part of the center region (IV). The variation of the scaling exponents with the compressibility is the most remarkable in the zone I and III . Finally, it is found that the most intermittent region exactly coincides with the location of the maximum Reynolds shear stress.EI03307-3114