In typical turbulent flows, noncontinuum effects are extremely small and hence can be ignored. However, for some high-Mach-number flows, the Kolmogorov length scale is of the same order as the molecular mean free path, which could introduce noncontinuum molecular-level effects into the turbulent energy cascade. To investigate this, the compressible Taylor-Green vortex flow is simulated for near-continuum conditions using both noncontinuum molecular gas dynamics (direct simulation Monte Carlo method) and continuum computational fluid dynamics (direct numerical simulation of the Navier-Stokes equations). Although the energy-decay histories are basically the same, molecular-level fluctuations are observed to break the symmetries of the initial conditions and thereby produce different but statistically similar routes (based on velocity spectra) from the initial nonturbulent flow to the long-time turbulent flow.

中文翻译：

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连续体边缘的湍流

在典型的湍流中，非连续性影响非常小，因此可以忽略。但是，对于某些高马赫数流，Kolmogorov长度尺度与分子平均自由程相同，这可能将非连续谱的分子水平效应引入湍流能级联中。为了对此进行研究，使用非连续分子气体动力学（直接模拟蒙特卡洛方法）和连续计算流体力学（Navier-Stokes方程的直接数值模拟）对近连续条件下的可压缩泰勒-格林涡流进行了模拟。尽管能量衰减的历史基本相同，