Numerical investigation of the possibility of macroscopic turbulence in porous media: a direct numerical simulation study
Numerical investigation of the possibility of macroscopic turbulence in porous media: a direct numerical simulation study
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DOI：
10.1017/jfm.2015.9
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发表时间：
2015-02
影响因子：
3.7
通讯作者：
Yan Jin;M. Uth;Andrey V. Kuznetsov;Heinz Herwig
中科院分区：
文献类型：
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作者：
Yan Jin;M. Uth;Andrey V. Kuznetsov;Heinz Herwig
当多孔介质中的湍流被数值确定时，关键的问题是湍流模型是否应该只考虑尺寸限制在孔尺度的湍流结构，或者湍流结构的尺寸是否可以超过孔尺度。后者意味着在多孔介质中存在宏观湍流，当湍流涡超过孔隙尺寸时。为了确定多孔介质中湍流结构的真实的尺寸，我们通过直接数值模拟（DNS）计算来模拟湍流，从而避免任何类型的湍流建模。通过这项研究，首次使用DNS计算，我们提供了多孔介质中湍流的基准数据。由于完美的DNS计算需要分辨率的尺度下降到柯尔莫哥洛夫尺度，往往只能得到近似的DNS解决方案，特别是对于高雷诺数。这是占通过使用和比较两种不同的DNS方法，有限体积法（FVM）与网格细化对壁和晶格玻尔兹曼方法（LBM）与相等的网格分布。固体基质由大量周期性排列的矩形棒模拟。在周期性边界条件的解决方案域中的酒吧的数量被系统地减少，直到找到一个最小的尺寸，不抑制任何大规模的湍流结构。为了回答多孔介质中是否存在宏观湍流的问题，确定了两点关联、积分尺度和能谱。
Abstract When a turbulent flow in a porous medium is determined numerically, the crucial question is whether turbulence models should account only for turbulent structures restricted in size to the pore scale or whether the size of turbulent structures could exceed the pore scale. The latter would mean the existence of macroscopic turbulence in porous media, when turbulent eddies exceed the pore size. In order to determine the real size of turbulent structures in a porous medium, we simulated the turbulent flow by direct numerical simulation (DNS) calculations, thus avoiding turbulence modelling of any kind. With this study, which for the first time uses DNS calculations, we provide benchmark data for turbulent flow in porous media. Since perfect DNS calculations require the resolution of scales down to the Kolmogorov scale, often only approximate DNS solutions can be obtained, especially for high Reynolds numbers. This is accounted for by using and comparing two different DNS approaches, a finite volume method (FVM) with grid refinement towards the wall and a lattice Boltzmann method (LBM) with equal grid distribution. The solid matrix was simulated by a large number of rectangular bars arranged periodically. The number of bars in the solution domain with periodic boundary conditions was reduced systematically until a minimum size was found that does not suppress any large-scale turbulent structures. Two-point correlations, integral length scales and energy spectra were determined in order to answer the question of whether or not macroscopic turbulence can be found in porous media.