不同相位壁面局部微振动诱导边界层大涡结构

以平板边界层Blasius解为基本流,利用直接数值模拟的方法求解三维不可压缩N-S方程,研究了边界层中不同初始相位壁面局部微振动诱导大涡结构的过程。计算结果表明:壁面扰动初始相位为0或π,大涡结构的初始扰动速度场完全相反,初始相位为0时,大涡结构演化时无论其扰动速度幅值、高低速条纹结构,流向涡量均随时间的增加而增长,壁面平均切应力明显大于平板边界层流动,近壁平均速度剖面变得饱满;初始相位为π时,诱导形成的大涡结构较弱。壁面局部微振动可诱导边界层内形成大涡结构,大涡结构演化特性与局部微振动初始相位密切相关。

Coherent Structures Induced by Local Vibration on the Wall with Different Initial Phases in Boundary Layer

Coherent structures induced by local vibration on the wall with different initial phases are ir vestigated by direct numerical simulation to solve incompressible Navier-Stokes equation.The basic flow is taken to be the Blasius boundary layer of the flat plate.Results show that the initial distribution coherent structure disturbance velocity is almost adverse when the initial phase of the local vibration is qual to zero and π.If the initial phase of the local vibration is equal to zero,the disturbances amplitude higher and lower speed streaks,streamwise vortices are increased with the time.And average shear stresses on the wall are larger than that of the boundary layer,the profile of the streamwise velocit near the wall becomes plump.If the initial phase of the local vibration is π,the intensity of coherer structures is feeblish.Thus,the disturbance induced by local micro-vibration on the wall represents th form of coherent structures in the boundary layer,and different evolvement characters of the coherent structures are closely related to the initial phase of the local vibration.