Effect of Wettability on Two-Phase Flow Through Granular Porous Media: Fluid Rupture and Mechanics of the Media

Abstract

A key parameter with considerable influence on the spatial distribution of the fluid phases in porous media is the wettability. Understanding the effect of wettability on fluids’ distribution in three-dimensional (3D) porous media is critical to any phenomenon that involves multiphase flow in such media. To address the problem, we have carried out extensive computer simulations of two-phase flow in a 3D granular packing of grains and studied the effect of the wettability by varying the contact angle. To this end, the Immersed Boundary and Volume-of- Fluid approaches are coupled with the discrete element method (DEM). Five contact angles, covering a full range of wettability, are considered. We find that the wettability affects particle dynamics, such as the displacement of the grains, the contact force, and fluid velocity, and that rupture of the fluid can also occur in the pore space. Our results indicate that the volume of invading fluid injected into the system, the pressure on walls, and the injection surface decrease for larger contact angles. Most importantly, increasing the contact angle reduces the inter-particle interactions, whereas the drag force exhibits an opposite trend, leading to larger displacement of the particles. We also demonstrate and emphasize that some aspects of the effect of the wettability can only be observed in the 3D models of porous media and, thus, 2D models are inadequate.