Scale-dependent statistics of inertial particle distribution in high Reynolds number turbulence
Scale-dependent statistics of inertial particle distribution in high Reynolds number turbulence
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DOI：
10.1103/physrevfluids.6.064304
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发表时间：
2020-07
期刊：
影响因子：
--
通讯作者：
K. Matsuda;K. Schneider;K. Yoshimatsu
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文献类型：
--
作者：
K. Matsuda;K. Schneider;K. Yoshimatsu
本文提出了惯性颗粒分布的多尺度统计分析方法，以研究不可压各向同性湍流中颗粒聚集和空穴区的统计特征。本文对高雷诺数（Re_\lambda \gtrsim 200$）下的均匀各向同性湍流进行了三维直接数值模拟，Stokes数为0.05 $~ 5.0 $，惯性粒子数为10^9 $。正交小波分析，然后施加到计算的粒子数密度场。尺度相关的偏度和平坦度值的颗粒数密度分布的计算和雷诺数$Re\lambda$和斯托克斯数$St$的影响进行评估。对于$St \sim 1.0$，尺度依赖的偏度和平坦度值随着尺度的减小而变大，这表明在小尺度上的间歇性聚类。对于$St \le 0.2$，在中间尺度的平坦度，即尺度大于Kolmogorov尺度和小于流的积分尺度，随着$St$的增加而增加，并且偏度在中间尺度呈现负值。偏度的负值归因于空隙区域。这些结果表明，在中间销售的空隙区域是明显的，间歇性分布的小斯托克斯数。随着Re_\lambda$的增加，平坦度略有增加。对于$Re_\lambda \ge 328$，偏度在大尺度下显示为负值，这表明在大尺度下空洞区域明显，而在小尺度下团簇明显。
Multiscale statistical analyses of inertial particle distributions are presented to investigate the statistical signature of clustering and void regions in particle-laden incompressible isotropic turbulence. Three-dimensional direct numerical simulations of homogeneous isotropic turbulence at high Reynolds number ($Re_\lambda \gtrsim 200$) with up to $10^9$ inertial particles are performed for Stokes numbers ranging from $0.05$ to $5.0$. Orthogonal wavelet analysis is then applied to the computed particle number density fields. Scale-dependent skewness and flatness values of the particle number density distributions are calculated and the influence of Reynolds number $Re_\lambda$ and Stokes number $St$ is assessed. For $St \sim 1.0$, both the scale-dependent skewness and flatness values become larger as the scale decreases, suggesting intermittent clustering at small scales. For $St \le 0.2$, the flatness at intermediate scales, i.e. for scales larger than the Kolmogorov scale and smaller than the integral scale of the flow, increases as $St$ increases, and the skewness exhibits negative values at the intermediate scales. The negative values of the skewness are attributed to void regions. These results indicate that void regions at the intermediate sales are pronounced and intermittently distributed for such small Stokes numbers. As $Re_\lambda$ increases, the flatness increases slightly. For $Re_\lambda \ge 328$, the skewness shows negative values at large scales, suggesting that void regions are pronounced at large scales, while clusters are pronounced at small scales.