多模态RM不稳定性对初始扰动条件的依赖性分析

Analysis of Dependence of Multi-Mode Richtmyer-Meshkov Instability on Initial Conditions

利用可压缩多介质黏性流动和湍流大涡模拟程序MVFT,对多次冲击作用下的三维多模态Richtmyer-Meshkov(RM)不稳定性发展及其对初始扰动条件的依赖性进行了数值模拟分析。湍流混合区宽度在初始冲击后以幂次律增长,在反射冲击后和第一次反射稀疏波作用后,以具有不同增长因子的指数规律增长,在第一次反射压缩波作用后近似以线性规律增长;而湍流混合区统计量则以类似的规律衰减。多模态RM不稳定性发展对初始扰动条件有很强的依赖性,主要体现在初始冲击后至反射冲击前和反射冲击后至第一次反射稀疏波作用前这两个阶段,即在第一次反射稀疏波作用后,湍流混合区的发展逐渐失去对初始扰动条件的记忆。

Using the in-house large-eddy simulation code MVFT,we investigated the three-dimensional multi-mode Richtmyer-Meshkov （RM） instability under multiple impingements and its dependence on initial conditions. After the initial shock,the width of the turbulent mixing zone （TMZ） grows with time in power-law. After the reshock and the impingement of the first reflected rarefaction wave, the TMZ width grows with time in the exponential law but with different growth factors. After the impingement of the first reflected compression wave, it grows with time in an approximately linear fashion,and the statistical quantities in TMZ decay with time in a similar way. The evolution of multimode RM instability is greatly dependent on the initial conditions between the initial shock and the impingement of the first reflected rarefaction wave. After the impingement of the first reflected rarefaction wave, the evolution of the turbulent mixing zone has lost the memory of the effect exerted by the initial conditions.