可压缩等温Turbulence的密度概率分布：螺线管强迫与压缩强迫
The Density Probability Distribution in Compressible Isothermal Turbulence: Solenoidal versus Compressive Forcing
摘要：
采用高分辨率数值模拟方法研究了超声速湍流中气体密度的概率密度函数。在一个系统的研究中，我们比较了密度统计的可压缩湍流驱动通常采用螺线管强迫（发散自由）和压缩强迫（卷曲自由）。我们的结果是一致的研究使用螺线管强迫。然而，在相同均方根马赫数下，压缩力产生的密度分布要宽得多，其标准偏差要大3倍左右。对恒星形成分析模型中的标准偏差-马赫数关系进行了评述，并对现有的公式提出了修正，该修正考虑了湍流强迫的螺线管模式和压缩模式的比例。
英文摘要：
The probability density function (PDF) of the gas density in turbulent supersonic flows is investigated with high-resolution numerical simulations. In a systematic study, we compare the density statistics of compressible turbulence driven by the usually adopted solenoidal forcing (divergence-free) and by compressive forcing (curl-free). Our results are in agreement with studies using solenoidal forcing. However, compressive forcing yields a significantly broader density distribution with standard deviation ~3 times larger at the same rms Mach number. The standard deviation-Mach number relation used in analytical models of star formation is reviewed and a modification of the existing expression is proposed, which takes into account the ratio of solenoidal and compressive modes of the turbulence forcing.
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