Direct Pore-Scale Modeling of Nanoconfined Liquid Transport in Multicomponent Porous Media Considering Microscale Effects

Summary Liquid/solid interactions, manifested as slip and nonuniform viscosity, substantially affect the flow and transport behaviors of confined liquids, which are further complicated by the ubiquitous nanopores in porous media due to their larger specific surface area. In this work, we present a novel direct numerical model, incorporating (i) slip boundary conditions represented by the Navier slip model, (ii) nonuniform viscosity for near-wall and bulk regions described by a newly defined viscosity field variable, and (iii) spatial heterogeneity of wettability associated with multicomponent nanoporous media, to simulate confined liquid flow. Our model is validated against analytical solutions for 2D confined channel flow. It is then applied to nanoporous media with multicomponent structures, where sensitivity analyses explore the impact of slip length and viscosity ratio on confined oil flow, as well as contact angle on confined water flow. The results reveal that the slip dominates mobility when the slip length is comparable to or larger than the pore size. Higher near-wall viscosity restricts the transport, while lower near-wall viscosity enhances it, as expected. Wettability heterogeneity is shown to reshape the preferential flow pathways for confined water, with hydrophobic minerals introducing flat parabolic velocity profiles and redistributing flow channels across the computational domain. This work provides an effective computational fluid dynamics (CFD) framework for understanding and predicting nanoconfined liquid transport in multicomponent porous systems relevant to geoenergy, environmental, and material applications.