Study of the pore size influence on infiltration of porous media considering capillary effect

The significance of pore size as a determinant in two-phase flow dynamics is widely acknowledged. However, the micro-scale behavior of flow including pore channel capillary and air-water interface development are not systematically interpreted due to the limitation of test and computation methodologies. In the present study, an investigation was conducted into the impact of varying pore throat widths on the flow of a two-phase fluid. For the investigation, numerical simulations were integrated with microfluidic experimentation to provide a comprehensive analysis. The results indicate that large pore diameters in porous media are associated with accelerated infiltration rates, leading to quicker stabilization. However, an inverse correlation exists between pore throat diameter and seepage area, with larger diameters yielding larger residual air areas. In this investigation, the “queuing effect” was observed across all tests, irrespective of pore throat diameter. Water initially permeated the central region of the pore network, sequentially inducing a breakthrough in adjacent pores. It was found that smaller pore throat diameters necessitated higher breakthrough pressures. Consistently, under unchanged inlet flow rates, narrower channels exhibited greater capillary resistance, impeding water flow. Specifically, for the four models with increasing pore throat widths, the critical capillary resistances are decreasing continuously from 87.6 to 38.2 Pa ultimately.