On the Effect of Flow Regime and Pore Structure on the Flow Signatures in Porous Media
On the Effect of Flow Regime and Pore Structure on the Flow Signatures in Porous Media
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流动形态和孔隙结构对多孔介质流动特征的影响
DOI：
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
M. Mousavi Nezhad
中科院分区：
文献类型：
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作者：
Mehrdad Vasheghani Farahani;M. Mousavi Nezhad
在这项研究中，格子玻尔兹曼方法（LBM）是用于三维模拟的流体流动通过两个多孔结构，由具有相同直径的颗粒组成：（i）均匀的多孔域，其中的颗粒被放置在一个简单的立方堆积配置，和（ii）随机堆积的多孔域。考虑使用超细网格尺寸，以雷诺数（）的三个数量级进行模拟，涵盖层流到湍流状态，并捕获不同的流动特征。孔隙速度场的推导，并分析其样本概率密度函数（PDF）随时间的推移，调查流动的动力学。的PDF的分析清楚地表明，停滞区发挥了显着的作用，在孔隙流场的形成，表现为多模态PDF，和多孔介质中的速度分布在不同的不能由一个单一的PDF模型的特点，无论孔隙结构。虽然在停滞区和固体边界附近的速度主要是由粘性力的影响，并表现出幂律PDF在不同的，在主要（优先）的流动路径远离边界的速度被证明是由惯性力的影响，因此具有指数PDF时低。然而，在高的情况下，取决于多孔结构的弯曲度，速度可以表现出指数或甚至拉普拉斯PDF。
In this study, lattice Boltzmann method (LBM) is utilised for three-dimensional simulation of fluid flow through two porous structures, consisting of grains with the same diameter: (i) a homogeneous porous domain, in which the grains are placed with a simple cubic packing configuration, and (ii) a randomly-packed porous domain. An ultra-fine mesh size is considered to perform the simulations in three orders of magnitude of Reynolds number (), covering laminar to turbulent flow regimes, and capture different flow signatures. Pore velocity fields are derived, and their sample probability density functions (PDF) are analyzed versus time to investigate the dynamics of the flow. The analysis of the PDFs clearly shows that stagnant zones play a significant role in the formation of the pore flow fields, manifested by multimodal PDFs, and the distribution of the velocities in porous media at various cannot be characterized by a single PDF model regardless of the pore structure. While the velocities at the stagnant regions and in the vicinity of the solid boundaries are primarily affected by the viscous forces and exhibit a power-law PDF at different , the velocities in the main (preferential) flow pathways away from the boundaries are shown to be influenced by the inertial forces, hence having an exponential PDF when is low. At high, however, depending on the tortuosity of the porous structure, the velocities may exhibit an exponential or even Laplace PDF.