关键词: 标度律, 直接数值模拟, 可压缩槽道湍流, 扩展自相似模型

Abstract: 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+≈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 (Ⅲ); 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.

Key words: scaling law, direct numeric simulation, compressible channel flow, extended self similarity