空间发展混合流的大涡模拟

采用大涡模拟方法数值模拟了空间发展混合流，通过在平均流中引入小扰动，研究了混合流大涡结构的产生和演化过程，捕捉了展向涡的卷起、配对、合并，以及二次流向涡的出现等大尺度的三维拟序结构。与实验及直接数值模拟的结果相比，吻合程度较好，表明本文所采用的LES方法对湍流的数值模拟是切实可行的。

Large-eddy simulation of a spatially developing mixing layer

Large eddy simulations of three dimensional spatially developing mixing layer with mixing transition are conducted to investigate the vortex structure of a mixing layer , their evolution and the budgets of momentum thickness, Reynolds shear stress and turbulent diffusion velocity. The numerical simulation is begun from a few low-wavenumber derived from linear stability theory in addition to the mean velocity. The coherent structure, such as the spanwise vortices(rollers), the pairing of the rollers(i.e. corotation and amalgamation of neighboring rollers)and the secondary streamwise vortex structure have been observed in present simulation. The physics captured in the present LES are consistent with the experiment and the DNS, but at a significant fraction of the DNS cost.