Anomalous eddy viscosity for two-dimensional turbulence
Anomalous eddy viscosity for two-dimensional turbulence
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DOI：
10.1063/1.4916956
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发表时间：
2015-04
影响因子：
4.6
通讯作者：
T. Iwayama;S. Murakami;Takeshi Watanabe
中科院分区：
文献类型：
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作者：
T. Iwayama;S. Murakami;Takeshi Watanabe
本文研究了广义二维流体的涡粘性。广义二维流体的控制方程是一个不可压缩速度作用于一个活动标量q的平流方程。q与流函数的关系为q = −（−。这里，α是一个真实的数。当广义涡度拟能谱Qα（k）的演化方程在一个波数kc处截断时，研究了截断波数大于kc的模对波数小于kc的广义涡度拟能谱动力学的影响.这里，我们把截断对Qα（k）（k < kc）的动力学的影响称为涡动粘性。我们的动机是检验涡动粘性是否可以用正态扩散来表示。使用涡阻尼准正常马尔可夫（EDQNM）封闭近似方程涡度拟能谱的渐近分析，我们表明，即使波数的兴趣k足够小于KC，涡粘性...
We study eddy viscosity for generalized two-dimensional (2D) fluids. The governing equation for generalized 2D fluids is the advection equation of an active scalar q by an incompressible velocity. The relation between q and the stream function ψ is given by q = − (−∇2)α/2ψ. Here, α is a real number. When the evolution equation for the generalized enstrophy spectrum Qα(k) is truncated at a wavenumber kc, the effect of the truncation of modes with larger wavenumbers than kc on the dynamics of the generalized enstrophy spectrum with smaller wavenumbers than kc is investigated. Here, we refer to the effect of the truncation on the dynamics of Qα(k) with k < kc as eddy viscosity. Our motivation is to examine whether the eddy viscosity can be represented by normal diffusion. Using an asymptotic analysis of an eddy-damped quasi-normal Markovian (EDQNM) closure approximation equation for the enstrophy spectrum, we show that even if the wavenumbers of interest k are sufficiently smaller than kc, the eddy viscosity...