Non-Kolmogorov scaling for two-particle relative velocity in two-dimensional inverse energy-cascade turbulence
Non-Kolmogorov scaling for two-particle relative velocity in two-dimensional inverse energy-cascade turbulence
复制标题
二维逆能量级联湍流中两粒子相对速度的非柯尔莫哥洛夫标度
DOI：
10.1103/physrevfluids.5.054601
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发表时间：
2020
影响因子：
2.7
通讯作者：
and Sadayoshi Toh
中科院分区：
文献类型：
--
作者：
Tatsuro Kishi;Takeshi Matsumoto;and Sadayoshi Toh
本文用数值方法研究了二维逆能量级联湍流中拉格朗日粒子对的相对色散。在Richardson-Obukhov相对分离定律的背后，我们发现相对速度的二阶矩具有与基于Kolmogorov唯象学的预测不同的时间标度指数。结果还表明，相对速度的概率分布函数的时间演化是自相似的。研究结果是通过执行Richardson-Obukhov定律，无论是考虑一个特殊的初始分离或条件抽样。特别是，我们证明了条件采样消除了分离和相对速度的统计的初始分离依赖性。此外，我们证明了条件统计是强大的，相对于所涉及的参数的变化，以及从采样中删除的对的数量减少时，雷诺数的增加。我们还讨论了作为条件抽样的结果获得的见解。
Herein we numerically examine the relative dispersion of Lagrangian particle pairs in two-dimensional inverse energy-cascade turbulence. Behind the Richardson-Obukhovlaw of relative separation, we discover that the second-order moment of the relative velocity have a temporal scaling exponent different from the prediction based on the Kolmogorov's phenomenology. The results also indicate that time evolution of the probability distribution function of the relative velocity is self-similar. The findings are obtained by enforcing the Richardson-Obukhov law either by considering a special initial separation or by conditional sampling. In particular, we demonstrate that the conditional sampling removes the initial-separation dependence of the statistics of the separation and relative velocity. Furthermore, we demonstrate that the conditional statistics are robust with respect to the change in the parameters involved, and that the number of the removed pairs from the sampling decreases when the Reynolds number increases. We also discuss the insights gained as a result of conditional sampling.