Two-point vorticity statistics in the inverse cascade of two-dimensional turbulence
Two-point vorticity statistics in the inverse cascade of two-dimensional turbulence
复制标题
二维湍流逆级联中的两点涡度统计
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
M. Wilczek
中科院分区：
文献类型：
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作者：
R. Friedrich;M. Vosskuhle;O. Kamps;M. Wilczek
本文用概率密度函数（PDF）对二维湍流逆能量级联中的两点涡量统计进行了统计分析。PDF的演化方程推导出的Lundamental-Monin-Novikov层次的框架中，并与直接数值模拟（DNS）的帮助下，研究了未封闭的条款。此外，在高斯近似下评估未闭合项，并与DNS结果进行比较。结果表明，统计方程可以用屏蔽涡的动力学来解释。两点统计与具有屏蔽速度场的两点涡的动力学有关，其中源自湍流环境的两点涡的有效相对运动被确定为逆叶栅动力学的主要特征。
A statistical analysis of the two-point vorticity statistics in the inverse energy cascade of two-dimensional turbulence is presented in terms of probability density functions (PDFs). Evolution equations for the PDFs are derived in the framework of the Lundgren–Monin–Novikov hierarchy, and the unclosed terms are studied with the help of direct numerical simulations (DNS). Furthermore, the unclosed terms are evaluated in a Gaussian approximation and compared to the DNS results. It turns out that the statistical equations can be interpreted in terms of the dynamics of screened vortices. The two-point statistics is related to the dynamics of two point vortices with screened velocity field, where an effective relative motion of the two point vortices originating from the turbulent surroundings is identified to be a major characteristics of the dynamics underlying the inverse cascade.