Modeling and Measurement of Pressure-Driven Transport in Hydrophobic Sinusoidal Capillaries

In this study, we investigate how channel geometry and surface wettability affect flooding resistance under pressure-driven flow. Using numerical simulations and synchrotron-based X-ray imaging, we examine the interplay between sinusoidal capillary architecture and hydrophobic surface treatments. We compare sinusoidal channels with moderate contact angles to straight channels with stronger hydrophobic coatings. Our findings reveal that geometric design alone can delay fluid intrusion to a comparable or greater extent than aggressive surface modifications. This suggests that sinusoidal geometry passively increases breakthrough resistance by altering local curvature and capillary pressure profiles. Importantly, these results challenge the conventional modeling of porous media as bundles of straight capillaries, pointing instead to a more nuanced design strategy where architecture and materials jointly dictate transport behavior. By leveraging geometry rather than relying solely on surface chemistry, this work presents a robust, passive approach for maintaining phase separation in capillary-driven systems—offering potential benefits for gas diffusion layers, membrane interfaces, and other multiphase applications.