Insight into the coupling effect of tortuosity and percolation on the permeability of overlapping ovoidal particle systems

Abstract

In general, porous media can be represented by the overlapping particle packing systems, where the overlapping-particles themselves are the pore phase that permit fluid flow. A fundamental yet unresolved topic has been determining the percolation threshold and tortuosity of the porous media with anisotropic pores, as well as their quantitative implications on permeability. This work calculates the percolation threshold, tortuosity, and permeability of overlapping ovoidal particle packing systems by theoretical and numerical approaches. To determine the tortuosity, the theoretical percolation-based tortuosity model and numerical direct shortest path searching method are used. And a modified tortuosity formula is developed to characterize how pore shape affect the tortuosity. Then, the permeability of porous media is numerically obtained by the lattice Boltzmann method. According to the obtained tortuosity and permeability, a modified Kozeny-Carman (K-C) equation for porous media is proposed, and the modified K-C equation's dependability is verified.