【摘要】 本文用二次稳定性理论研究自由剪切湍流中周期性基本流空间增长扰动的稳定性。数值结果表明三维亚谐扰动对横向波数有很强的选择性，二维亚谐波的空间增长率最大。与之相反，基本模式的三维扰动在很大的波数范围内存在不稳定性，证明β＝０时存在”转移”不稳定性；当ＫＨ波的幅值Ａ≥０．０６时出现分叉现象。更多还原

【Abstract】 The secondary instability theory is used to study the behavior of spatially growing disturbance in free turbulent shear layer. The numerical results indicate that secondary instability of subharmonic mode shows a strong choice of spanwise wavenumber and the maxinum growth rate occurs in two dimensional case. In contrast to that seoondary instabilities of the fundamental mode occur in a wide scope of spanwise wavenumber We have found so called’ translative instability’at β=0 and bifurcation phenomenon for amplitude of the KH wave larger than 0.06.更多还原