Pore-scale simulation of liquid retention in stratified porous microstructures

We computationally investigate how a thin, fine-porosity interlayer—a distinct region of smaller pores embedded within a larger-pore matrix—reshapes liquid retention patterns in stratified porous media under both forced drainage and convective drying. To enable more robust comparisons of the results, we generate three artificial porous microstructures, each with an initial porosity of ϕ = 0.6 but differing pore network configurations. Stratification is achieved by adding a layer of finer pores onto the walls of these structures, forming an interlayer of variable thickness (δ). By adjusting δ, the overall porosities of the stratified media are set to 0.6 (δ = 0), 0.49, and 0.43, respectively. Using a combination of multiphase, multicomponent lattice-Boltzmann simulations and pore-network modeling, we demonstrate that the fine-pore interlayer acts as a capillary reservoir, consistently altering liquid retention patterns in both drainage and drying scenarios. To facilitate further research, we release our open-source solver and data processing toolkit for reproducible, high-fidelity studies of multiphase transport in complex porous materials.