圆柱近尾迹湍流涡结构的直接数值模拟

本文运用谱元方法对圆柱尾流进行直接数值模拟。通过对中等Re数（1000）时的圆柱近尾迹湍流涡结构的演变系统细致的研究,经过长时间流动计算,用速度矢量及相应涡结构示意图显示主涡,二次涡结构的相互作用,显示整个尾迹涡结构在一个周期内的演变过程,获得了在实验中难以清楚观察到的近壁流动特征。本文得到圆柱近壁处二次涡形成有两种不同的机理,并总结出涡的合并所需要的条件。

PHYSICAL ANALYSIS OF VORTEX SHEEDING IN THE NEAR WAKE OF A CIRCULAR CYLINDER BY DIRECT NUMERICAL SIMULATION

Spectral element method for solution of the Navier-Stokes Equations is first employed in the investigation of wake shedding. The vortex structure transition near a cylinder is described in detail at Re of 1000. By long time computing, the inaction between main vortex and second vortex near cylinder is shown by a series of sketch pictures of their velocity vector during one period, which out of experimental research. It is concluded that there are two different mechanisms of the second vortex birth. Moreover, the vortex merging condition is given.