可压缩自由混合层中的输运平衡

Transport budget in a compressible free mixing layer

为研究可压缩混合层中的输运特性 ,该文采用气动BGK格式模拟了超音速来流条件下的二维平面可压缩混合层的空间发展 ,给出了湍能、雷诺应力和动量输运方程中各项的分布情况。各平衡方程中粘性耗散项和粘性扩散项都很小。湍能主要是通过对流、湍流扩散和压力扩散进行输运 ;切应力输运方程中主要是生成项与压力扩散项和压力 -应变关联项的平衡 ;雷诺应力 (1,1)分量输运方程中以生成项和压力 -应变关联项为主 ;雷诺应力 (2 ,2 )分量输运方程中主要是压力 -应变关联项与湍流扩散项和压力扩散项之间的平衡。

The transport characteristics of compressible flow were studied using the gas kinetic BGK scheme to simulate a 2 D planar compressible mixing layer with supersonic inflow. The results show the importances of every term in the transport equation including the turbulent kinetic energy, the Reynolds stresses and the momentum transport. The viscous diffusion and dissipation terms are both very small. Turbulent energy is transported by convection, turbulent diffusion and pressure diffusion. The production term, the pressure diffusion term and the pressure strain correlation term dominate the shear stress equation. The (1,1) component of the Reynolds stress is dominated by the production term and the pressure strain correlation term. In the transport equation for the (2,2) component, the pressure diffusion term is as large as the turbulent diffusion term which are both balanced by the pressure strain correlation term.