Wetting Front Dynamics in Isotropic Porous Media

TL;DR

This paper introduces a novel modeling approach for wetting front dynamics in isotropic porous media, linking pore-scale physics and threshold phenomena to Darcy-scale behavior, enabling more accurate and adaptable simulations.

Contribution

It develops a new technique of conjugate problems to incorporate pore-scale physics and threshold effects into Darcy-scale wetting front models.

Findings

The approach captures pore-scale threshold phenomena affecting wetting front motion.

It provides a flexible framework for constructing increasingly complex models.

The method links pore-scale physics with Darcy-scale wetting dynamics.

Abstract

A new approach to the modelling of wetting fronts in porous media on the Darcy scale is developed, based on considering the types (modes) of motion the menisci go through on the pore scale. This approach is illustrated using a simple model case of imbibition of a viscous incompressible liquid into an isotropic porous matrix with two modes of motion for the menisci, the wetting mode and the threshold mode. The latter makes it necessary to introduce an essentially new technique of conjugate problems that allows one to link threshold phenomena on the pore scale with the motion on the Darcy scale. The developed approach (a) makes room for incorporating the actual physics of wetting on the pore scale, (b) brings in the physics associated with pore-scale thresholds, which determine when sections of the wetting front will be brought to a halt (pinned), and, importantly, (c) provides a regular framework for constructing models of increasing complexity.