Experimentally consistent large-eddy simulation of re-shocked Richtmyer–Meshkov turbulent mixing
Experimentally consistent large-eddy simulation of re-shocked Richtmyer–Meshkov turbulent mixing
复制标题
实验一致的再冲击 Richtmyer-Meshkov 湍流混合的大涡模拟
DOI：
10.1063/5.0129595
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发表时间：
2022
影响因子：
4.6
通讯作者：
You-Sheng Zhang
中科院分区：
文献类型：
--
作者：
Meng-Juan Xiao;Ze-Xi Hu;Zi-Huan Dai;You-Sheng Zhang
再冲击Richtmyer-Meshkov（RM）混合是与实际混合问题紧密相关的基本物理过程，因为它涉及所有三种经典不稳定性，即，瑞利-泰勒、里希特迈尔-梅什科夫（RM）和开尔文-亥姆霍兹不稳定性。准确预测其混合宽度（MW）具有重要意义。然而，令人满意的预测尚未实现与纯（不受湍流模型的约束）大涡模拟（LES），其中预测MW和其增长率被过度预测。在文献中，我们通过两个关键的改进来解决这个问题。首先，速度扰动，而不是常用的界面扰动，是适应于产生一个初始的扰动幅度相媲美的相应的实验。其次，建立了一个新的大涡模拟模型，引入了亚网格动能方程，并动态确定了模型系数。这里的关键改进是要考虑的浮力生产效果的封闭形式，这被证明是一个主要的机制产生湍流的再冲击RM混合，仍然是重要的，即使在最小的尺度。因此，一个一致的预测MW与实验实现使用本纯LES的第一次。
Re-shocked Richtmyer–Meshkov (RM) mixing is a fundamental physical process tightly related to practical mixing problems, as it involves all three classical instabilities, i.e., Rayleigh–Taylor, Richtmyer–Meshkov (RM), and Kelvin–Helmholtz instabilities. An accurate prediction of its mixing width (MW) is of significant importance. However, satisfactory prediction has not yet been achieved with the pure (not constrained by turbulence models) large-eddy simulation (LES), by which both the predicted MW and its growth rate are over-predicted. In the literature, we solve this problem by two key improvements. First, velocity perturbation, instead of the commonly used interface perturbation, is adapted to produce an initial magnitude of perturbation comparable to the corresponding experiments. Second, a new LES model is developed, with a sub-grid kinetic energy equation introduced and model coefficients dynamically determined. The key improvement here is to consider the buoyancy production effect in the closure form, which is proved to be one of the dominant mechanisms generating turbulence for the re-shocked RM mixing and remains important even at the smallest scales. Consequently, a consistent prediction of MW with experiments is realized using the present pure LES for the first time.