混合层流动的数值模拟

Numerical simulation of mixing layer flow

对混合层流动进行了数值模拟。采用了离散涡方法。计算中采用扩散速度法处理粘性作用项。计算结果表明：与通常采用随机涡方法或核膨胀法处理粘性作用项相比，采用扩散速度法的计算结果与实验更吻合，同时更准确地反映了混合层流动的自相似性。在混合层流动中，邻近大尺度涡结构之间存在着连续不断的合并；采用二维离散涡方法预报的横向脉动速度均方根大于实验值是由二维离散涡方法忽略了真实流动的三维特性引起的。

The mixing layer flow was numerically simulated by the discrete vortex method, in which the diffusion velocity method was adopted to model the viscosity. The results by diffusion velocity method agreed with the experiments better than that by random vortex method and core spreading method, and showed the self similarity of mixing layer flow more perfectly. The results also indicated that the over estimation of the root of mean square is attributed to the effect of three dimensionality existing in actual flow, but neglected by two dimensional discrete vortex method.