Geometry models of porous media based on Voronoi tessellations and their porosity-permeability relations
Geometry models of porous media based on Voronoi tessellations and their porosity-permeability relations
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DOI：
10.1016/j.camwa.2015.09.009
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发表时间：
2016-07-01
影响因子：
2.9
通讯作者：
Yin, Xiaolong
中科院分区：
文献类型：
--
作者：
Xiao, Feng;Yin, Xiaolong
在本文中，我们提出的方法，直接模拟多孔介质的随机结构，使用Voronoi镶嵌。生成了三种基本结构，它们对应于具有交叉断裂（颗粒状）、互连管（管状）和纤维（纤维状）的多孔介质几何形状。通过这些模型的流体流动由大规模并行化的格子Boltzmann代码求解。建立了这些基本几何模型的孔隙度-渗透率关系。据发现，颗粒和管状的几何形状，比表面积是一个关键的结构参数，可以把它们的孔隙度-渗透率关系在一个统一的Kozeny-Carman方程。一个连接的裂缝网络，叠加在基本Voronoi结构，增加了无量纲渗透率相对于Kozeny-Carman方程;孤立的大孔隙（溶洞），另一方面，降低了无量纲渗透率相对于Kozeny-Carman方程。然而，Kozeny-Carman方程不能区分具有嵌入式部分穿透裂缝的非均质结构。纤维几何形状的孔隙率-渗透率关系一般与简单立方、体心立方和面心立方模型的孔隙率-渗透率关系一致。然而，在稀释的限制，对固体分数的依赖是较弱的Voronoi几何形状，随机互连的纤维之间的流体动力学相互作用弱于理想化的模型。(C)2015爱思唯尔有限公司版权所有。
In this paper, we present methods that directly model the random structure of porous media using Voronoi tessellations. Three basic structures were generated and they correspond to porous medium geometries with intersecting fractures (granular), interconnected tubes (tubular), and fibers (fibrous). Fluid flow through these models was solved by a massively parallelized lattice Boltzmann code. We established the porosity-permeability relations for these basic geometry models. It is found that, for granular and tubular geometries, the specific surface area is a critical structural parameter that can bring their porosity-permeability relations together under a unified Kozeny-Carman equation. A connected fracture network, superimposed on the basic Voronoi structure, increases the dimensionless permeability relative to the Kozeny-Carman equation; isolated large pores (vugs), on the other hand, decreases the dimensionless permeability relative to the Kozeny-Carman equation. The Kozeny-Carman equation, however, cannot distinguish a heterogeneous structure with an embedded partially penetrating fracture. The porosity-permeability relation for fibrous geometries in general agrees with those established for Simple-cubic, body-centered cubic, and face-centered cubic models. In the dilute limit, however, the dependence on the solid fraction is weaker in Voronoi geometries, indicating weaker hydrodynamic interactions among randomly interconnected fibers than those in the idealized models. (C) 2015 Elsevier Ltd. All rights reserved.