近壁湍流边界层壁面局部扰动诱导形成相干结构的动力学模型

Dynamic model of coherent structure by local disturbance in wall region of a turbulent boundary layer

在壁面局部脉冲扰动作用下,采用直接数值模拟的方法,数值研究了湍流边界层近壁区两个相干结构形成的理论机制和非线性作用问题。然后,通过数值计算的手段,进一步探讨了近壁湍流边界层流中两个相干结构之间的非线性作用机理,分别确定它们在流向、展向方向上排列的不同结构类型分布的两个相干结构之间相互作用的效果有何区别以及它们之间间距的大小对相干结构的产生和发展有什么影响,从而可能合理地解释平面剪切湍流中低速条纹结构出现的原因。

With the function of local wall impulsive disturbance, the formation mechanism of two coherent structures and the their nonlinear interaction in the near wall region of a turbulent boundary layer were studied by direct numerical simulations. Thus, different effects of interaction within two coherent structures and their impact on the occurrence and development of coherent structures regarding their distance had been determined in terms of their arrangement in the streamwise and spanwise directions. Therefore, the formation of low speed streak structures in planar shear flow in a turbulence can be explained reasonablly.