Evaluation of the interFoam solver in the prediction of immiscible two-phase flow in imbibition and drainage on the pore-doublet system

Abstract

Drainage and imbibition at low to moderate capillary number, are very important phenomena, in which the SCAL data are derived. In this venue, there is an increasing trend to apply computational fluid dynamic models at pore scale to extract the required parameters for multiphase flow study. Before applying these methods, their abilities to capture the real performance of fluids at the pore scale with corresponding capillary numbers should be validated. Moreover, due to the dimensional difference from pore to core scale, rigorous statistical methods are required to successfully extract the corresponding SCAL parameters. Hence for any model, before constructing any SCAL data via digital methods, validation at the pore scale along with the investigation of the possible effect of the dimensional change from pore to core scale are significant priorities. In this study, the performance of interFoam, a solver for immiscible two-phase flow from OpenFOAM, at the pore scale is evaluated. An image of the pore doublet system is digitized and meshed with different resolutions to capture the contact angle movement. The average pore diameters are different, and the pore diameter pathway varies. The experimental results are extracted from an article, which extensively performed the tests for different imbibition and drainage regime on this pore doublet system. Moreover, a sensitivity analysis on mesh geometry, refinement near boundaries, and contact angle is conducted. The drainage simulation and experimental results in the pore doublet system are in good agreement with each other. As expected, the displacement happens in the larger diameter and bypasses the wetting fluid in the narrow constriction. In imbibition, the displacement first takes place in the smaller constriction and then the wetting phase starts invading the larger diameter pore. From the sensitivity analysis, it is concluded that the instability of the front is mainly related to the slip condition at the walls. Moreover, the spreading of wetting film near the wall is prevalent at very low contact angles. The results show that the solver can predict the flow behavior in imbibition and drainage on the pore doublet system and the results are comparable with the experiments.