Three-dimensional rotating Couette flow via the generalised quasilinear approximation
Three-dimensional rotating Couette flow via the generalised quasilinear approximation
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DOI：
10.1017/jfm.2016.727
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发表时间：
2017-01-10
影响因子：
3.7
通讯作者：
Marston, J. B.
中科院分区：
文献类型：
--
作者：
Tobias, S. M.;Marston, J. B.
我们检验了Marston等人提出的广义拟线性(GQL)近似的有效性。(物理。《莱特牧师》，第116卷(21)，2016年，214501)。这种近似将变量在具有平移对称性的方向上分为大尺度和小尺度，并消除了只涉及小尺度的非线性相互作用。我们利用三维、湍流、旋转的Couette流作为一个范例问题。我们将直接数值解方程的结果与拟线性(QL)和GQL计算的结果进行了比较。在这个三维设置中，GQL近似在流方向和跨方向上都有截止波数的选择。我们证明了GQL近似显著地提高了平均流、谱和两点关联函数的精度，即使只包括几个流向和跨距模，但相对于在任何平移不变方向上是拟线性的模型而言。我们认为，这为利用GQL近似的直接统计模拟程序提供了重要支持。
We examine the effectiveness of the generalised quasilinear (GQL) approximation introduced by Marston et al. (Phys. Rev. Lett., vol. 116 (21), 2016, 214501). This approximation splits the variables into large and small scales in directions where there is a translational symmetry and removes nonlinear interactions involving only small scales. We utilise as a paradigm problem three-dimensional, turbulent, rotating Couette flow. We compare the results obtained from direct numerical solution of the equations with those from quasilinear (QL) and GQL calculations. In this three-dimensional setting, there is a choice of cutoff wavenumber for the GQL approximation both in the streamwise and in the spanwise directions. We demonstrate that the GQL approximation significantly improves the accuracy of mean flows, spectra and two-point correlation functions over models that are quasilinear in any of the translationally invariant directions, even if only a few streamwise and spanwise modes are included. We argue that this provides significant support for a programme of direct statistical simulation utilising the GQL approximation.