大涡结构在有压梯度边界层流中的演化机理  

Evolution of coherent structures in boundary layer with pressure gradients

作　　者：张艳梅[1] 陆昌根[1] 曹卫东[1] 

机构地区：[1]河海大学环境科学与工程学院,江苏南京210098

出　　处：《河海大学学报（自然科学版）》2007年第5期510-513,共4页Journal of Hohai University(Natural Sciences)

基　　金：国家自然科学基金资助项目(10272040;10672052);教育部博士点基金资助项目(20050294003)

摘　　要：采用直接数值模拟方法,研究大涡结构在不同压力梯度作用下的非线性演化特征.计算结果表明:在逆压梯度条件下,大涡结构幅值快速增长,形成很强的流向涡结构,雷诺应力迅速增加,这可能导致猝发现象的产生;与此相反,在顺压梯度边界层流中,大涡结构很难被激发起来,易于流体流动趋于稳定状态.这些结论与某些理论和试验结果一致.By use of direct numerical simulation method, the nonlinear evolution of coherent structures under different pressure gradients was studied. According to the result, the amplitude of coherent structures grows fast in a boundary layer with negative pressure gradients, then the streamwise vortex structure is formed, and Reynolds stress increases fast. These factors might result in the occurrence of turbulences. However, it is difficult for coherent structures to be excited in the boundary layer with positive pressure gradients, and thus, the flow is apt to become stable under such a condition. The numerical results agree well with those from theoretical analysis and experiments.

关 键 词：压力梯度 大涡结构 边界层 

分 类 号：O357.5[理学—流体力学]