近壁湍流边界层对称与非对称相干结构的形成机制分析

Analysis on formation mechanism of symmetrical and unsymmetrical coherent structure in the near wall region of turbulent boundary layer

提出某一种局部脉冲扰动为近壁湍流边界层对称和非对称相干结构产生的初始物理模型,采用直接数值模拟的方法,数值研究近壁湍流边界层对称与非对称相干结构的形成机制及发展规律,详细地分析对称与非对称相干结构的演化特征,确定非对称相干结构和对称相干结构哪一种情况更容易被激发产生以及激励快速增长的原因是什么?该问题的深入研究,为我们进一步理解和认识湍流的形成机理、演变过程以及湍流的能量、动量的输送规律等方面均起到十分重要的作用。

An initial physical model on the symmetrical and unsymmetrical coherent structure in the near wall region of turbulent boundary layer generated by a certain local impulse disturbance is proposed.Direct numerical simulation is used to analyze the formation mechanism and the development law of the symmetrical and unsymmetrical coherent structure in the near wall region of turbulent boundary layer,particularly the evolution characteristics of symmetrical and unsymmetrical coherent structure,so as to identify which structure is more likely to be stimulated and generate,and the reason of rapid increase of excitation.The thorough research enables better understanding of the formation mechanism and evolution process of turbulence,and is also important on the aspects of energy and momentum transports of turbulance.