【摘要】 采用大涡模拟方法研究了三维小扰动下 ,混合流场大尺度拟序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 ,分析了拟序结构与入口扰动方式之间的内在联系 ,再现了涡卷自身撕裂而引发转捩的现象。更多还原

【Abstract】 Large eddy simulations of a three dimensional spatially developing mixing layer are conducted to investigate the origin of the vortex structure of the mixing layer and its evolution to different inlet initial disturbances. The coherent structure, such as the spanwise vortices(rollers), the pairing of the rollers(i.e. co rotation and amalgamation of neighboring rollers) and the secondary streamwise vortex structure have been observed in the present simulation. These results suggest that there is an inherent relation between the large scale vortex structure and the inlet initial disturbances. A transition to turbulence triggered by vortices tearing has also been observed. The mechanisms responsible for the growth of three dimensionality and onset of transition to turbulence lay the foundations of controlling the evolution of the mixing layer.更多还原