Examination Of Capillary Regime In The Soil Water Retention Curve Using Multi-Phase Lattice Boltzmann Method

The soil water retention curve (SWRC) is a key constitutive relationship describing the behavior of variably saturated soils. Further insight into this behavior can be gained by studying the role of capillarity on pore adsorption. In this study, we employed a multi-phase lattice Boltzmann method (LBM) to investigate the effects of initial fluid density distribution on the capillary response of the system. The multi-phase LBM model was first validated against benchmark problems and was then employed to simulate a static particle array. The SWRCs were generated by recording the liquid pore pressure and the degree of saturation within a porous medium subjected to imbibition for two cases of initial fluid density distribution: randomized fluid density simulation (non-unified wetting front) and droplet simulation (unified wetting front). The results showed that the unified nature of the wetting front has a direct influence on the magnitude of the peak capillary response of the soil skeleton. The multi-phase LBM method is shown to be a promising tool to characterize capillary regime in partially saturated porous media. This modeling tool can be considered for future multi-scale numerical studies of multi-phase flow within porous media.