Immiscible fluid displacement: From pore doublets to porous media

Understanding multiphase flow in porous media is essential for diverse engineering applications, from large-scale carbon geosequestration to small-scale fuel cells. Poredoublet models, despite their geometrical simplicity, offer a powerful framework to study the complex interplay between capillary and viscous forces during multiphase flow. This work revisits some recent advances in the understanding of immiscible fluid displacement processes provided by pore-doublet studies, and highlights their ability to capture key interfacial phenomena such as Haines jumps and to map displacement regimes through phase diagrams. While these models do not capture the full heterogeneity of real porous systems, they often exhibit strong agreement with larger-scale observations. Recent advances in microfluidics fabrication techniques further enhance the capability and efficiency of using pore-doublet models to investigate immiscible displacement processes. Several promising research directions for extending pore-doublet approaches are identified. Document Type: Perspective Cited as: Wang, Z. Immiscible fluid displacement: From pore doublets to porous media. Capillarity, 2025, 15(1): 1-3. https://doi.org/10.46690/capi.2025.04.01