Dynamics of droplet and liquid layer penetration in three-dimensional porous media: A lattice Boltzmann study

Liquid penetration analyses for porous media are of great importance in a wide range of industrial applications including, but not limited to, water infiltration in complex soil, hydrocarbon recovery, and liquid seepage through sediments. Depicting the details of two-phase flow in porous media is challenging due to the complex fluid-solid interaction in porous structure. In the present work, we use the three-dimensional multiphase lattice Boltzmann model with a large density ratio to investigate the droplet and liquid layer penetration in complex porous media. It is found that lower porosity leads to larger interactions at the liquid-solid interface and causes stronger drag force acting on the droplet. Both hydrophobic and hydrophilic substrates tend to facilitate droplet migration from the outside to the inside of the porous media. Decreasing the interfacial tension enhances liquid deformation and results in more liquid breakup. Due to the large total momentum dissipation, an increased viscosity ratio causes a reduction of the penetration rate. Even with identical porosity, the pores in parallel to the gravitational force, compared with the perpendicular structure, make the drag force relatively smaller, leading to a faster penetration and stretching interfaces. Overall, this work not only demonstrates the capacity of the multiphase lattice Boltzmann method but also sheds some light on the mechanism of droplet and liquid layer penetration through the porous media. Published under license by AIP Publishing