振荡流底层拟序结构运动理论模式

湍流拟序结构是一种可检测的有序运动,在壁面湍流结构中往往表现出复杂的三维结构.针对对称振荡流(纯振荡流),建立了描述对称振荡流湍流拟序结构的理论模式,并对其特性进行了研究.探讨了振荡流拟序结构能够保持的雷诺数范围、拟序扰动波数范围以及所能激发不稳定拟序波的波数频率范围,分析了振荡流激发的二维扰动波与三维扰动波的相互关系以及拟序波的对称性特征、拟序扰动流速、雷诺应力、附加涡量的时空分布等.结果表明,对称性振荡流拟序结构不仅与通常研究的雷诺数等因素有关,而且与振荡频率有很大的关系.

Theoretical Model of Coherent Structure of Oscillatory Flow in Wave Boundary Layer

The coherent structure in the turbulence is a kind of detectable, orderly motion of the fluid. It always ap-pears as the complicated three-dimensional structure in the wall turbulence. With symmetric oscillatory flow as the object of study, a theoretical model that describes its coherent structure was established. The ranges of Reynolds num-bers, the wave number of the coherent disturbance and the frequency were investigated. Moreover, the relationship between the two-dimensional disturbance and the three-dimensional disturbance, the symmetric characteristics of the coherence structure and the spatial distribution of the disturbance velocity, Reynolds stress and additional vorticity were analyzed. The results show that the characteristics of the coherent structure of the symmetric oscillatory flow not only are related to such factors as Reynolds number, but also are closely related to the oscillatory frequency.