A Functional Relationship Between Capillary Pressure, Saturation, and Interfacial Area as Revealed by a Pore‐Scale Network Model

TLDR

Constitutive relationships for multiphase flow and transport are critical to hydrologic modeling. The study developed a network model to test the hypothesis linking capillary pressure, saturation, and interfacial area. The network model simulated microscale processes and applied volume averaging to derive macroscopic saturation and fluid‑fluid interfacial area per volume. The results confirm a smooth, complex functional relationship between capillary pressure, saturation, and interfacial area at the continuum scale, reinforcing constitutive theory and NAPL dissolution modeling.

Abstract

The constitutive relationships required for the parameterization of multiphase flow and transport problems are of critical importance to hydrologic modeling. Recently, a hypothesis has been developed that predicts a functional relationship between capillary pressure, saturation, and interfacial area. A network model was developed to test this hypothesis. Microscale physical processes were simulated and volume averaging was used to derive the macroscopic measures of saturation and fluid‐fluid interfacial area per volume of porous media. Results indicate that a smooth, though complex, functional relationship exists at the continuum scale. These results have direct relevance to constitutive theory and the modeling of nonaqueous phase liquid dissolution processes.