在亚音速turbulence的SPH模拟中解决高Reynolds numbers
Resolving high Reynolds numbers in SPH simulations of subsonic turbulence
摘要：
雷诺数的计算在湍流的数值模拟中是至关重要的，特别是对于亚音速流。对于光滑粒子流体动力学（SPH）与恒定的人工粘性系数α，它表明，在没有明确的物理粘性项的有效雷诺数的比例线性与马赫数相比，网格计划，其中的有效雷诺数在很大程度上是独立的流速。因此，与网格代码相比，α =1的SPH模拟在亚音速范围内的雷诺数较低，可能不足以解决湍流。这就解释了Bauer和Springel（2011，arXiv：1109.4413v1）未能在移动网格程序AREPO和GADGET SPH程序之间找到适合于星系间/星系团内介质的驱动亚音速（v ~ 0.3 cs）湍流模拟的一致性，据称SPH程序从根本上无法产生类似于柯尔莫哥洛夫的湍流级联。我们表明，湍流与Kolmogorov频谱可以很容易地恢复采用标准的方法减少α远离冲击。
英文摘要：
Accounting for the Reynolds number is critical in numerical simulations of turbulence, particularly for subsonic flow. For Smoothed Particle Hydrodynamics (SPH) with constant artificial viscosity coefficient alpha, it is shown that the effective Reynolds number in the absence of explicit physical viscosity terms scales linearly with the Mach number - compared to mesh schemes, where the effective Reynolds number is largely independent of the flow velocity. As a result, SPH simulations with alpha=1 will have low Reynolds numbers in the subsonic regime compared to mesh codes, which may be insufficient to resolve turbulent flow. This explains the failure of Bauer and Springel (2011, arXiv:1109.4413v1) to find agreement between the moving-mesh code AREPO and the GADGET SPH code on simulations of driven, subsonic (v ~ 0.3 c_s) turbulence appropriate to the intergalactic/intracluster medium, where it was alleged that SPH is somehow fundamentally incapable of producing a Kolmogorov-like turbulent cascade. We show that turbulent flow with a Kolmogorov spectrum can be easily recovered by employing standard methods for reducing alpha away from shocks.
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