Porosity and Material Disorder Drive Distinct Channelization Transition

TL;DR

This study develops a continuum model to understand how disorder in porous media influences flow channelization, revealing that even minimal heterogeneity can induce persistent channels.

Contribution

The paper introduces a new continuum framework that links pore-scale dynamics to macroscopic flow patterns, highlighting the distinct effects of different disorder sources on channelization.

Findings

Disorder in erosion resistance causes a discontinuous transition to localized flow.

Weak initial porosity fluctuations destabilize homogeneous flow.

Channelization can occur even in nearly uniform materials.

Abstract

Flow through porous media can reshape the medium through erosion and deposition, producing preferential flow channels across a wide range of natural and industrial systems. Yet the mechanisms by which spatial disorder triggers channelization remain unclear. Here we derive a continuum description for the coupled evolution of flow and porosity by coarse-graining pore-scale dynamics and validating the resulting model with pore-scale simulations. Using this framework, we show that different sources of disorder lead to qualitatively distinct behaviors. Disorder in erosion resistance produces a discontinuous transition to localized flow, with permanent channels appearing only above a finite disorder strength. In contrast, even extremely weak fluctuations in the initial porosity destabilize homogeneous flow and trigger persistent channelization. These results reveal an unexpected sensitivity of evolving porous media to structural heterogeneity, suggesting that channelization can arise generically even in nearly uniform materials.