【摘要】 依据Floquet理论建立三维亚谐扰动的控制方程,研究Falkner Skan流的二次稳定性问题。采用高精度的谱方法进行数值模拟,结合边界层特性有效地配置边界条件,引入不同类型压力梯度,研究在压力梯度下的二维有限振幅的Tollmien Schlichting(TS)波对三维亚谐扰动的产生、发展和演化的作用和影响。结果表明,顺压梯度的存在可以减缓二次不稳定的发生和演化,而逆压梯度却加速了二次不稳定性。更多还原

【Abstract】 For the FalknerSkan flow, the Floquet’s threedimensional linear stability theory is used and a set of stability equations have been constructed. The high accuracy method of using expansions in orthogonal functions is used. Based on the characteristic of the boundary layer, the boundary condition is arranged effectively. Different type of pressure gradient are used. On the boundary layer with pressure gradient, the effect of the twodimensional TollmienSchlichting wave with finite amplitude on growth and development of the subharmonic is studied. It can be seen from the calculations that the favorable pressure gradient can delay the instability and retard the occurrence of transient, yet the adverse pressure gradient accelerates the instability and promotes the transient of boundary layer.更多还原