三维超声速混合层内标量混合的大涡模拟

对三维对流马赫数0.62的超声速混合层流动的标量混合进行大涡模拟, 控制方程对流项采用五阶精度的WENO格式求解, 小尺度涡的作用采用一方程LDKM亚格子模型处理, 过滤后的组分方程中的亚格子组分对流通量采用梯度扩散模化.模拟得到了混合层流场大尺度拟序结构以及标量场的演化过程, 研究表明标量混合过程受混合层内涡系演化所控制, 标量场具有明显的三维特征.模拟得到的速度、组分及其脉动的统计时均结果和实验结果相符较好. 

Large eddy simulation of scalar mixing in a 3D supersonic mixing layer

Large eddy simulation was conducted to study the scalar mixing of a 3D supersonic shear layer with convective Mach number 0.62.Governing equations of large scale eddy were solved with fifth-order WENO scheme,and effect of small scale eddy was simulated by using localized dynamic kinetic subgrid scale model(LDKM).The subgrid convective species flux in the filtered species equation was modeled using gradient diffusion method.The results reveal the evolution of the vortex structure of the mixing layer and the scalar field.Simulations show that coherent structures dominate the scalar mixing and the instantaneous distribution of scalar field exhibits obvious 3D characteristics.Statistics such as mean and the root mean square(RMS)of the velocity and the scalar field compares well with the experimental measurements.