A model of dispersive transport across sharp interfaces between porous materials

TL;DR

This paper introduces a new model for dispersive transport across sharp interfaces in porous materials, explaining asymmetries observed in experiments through flux rectification and microscopic particle dynamics.

Contribution

It proposes a novel definition of solute flux across sharp interfaces and uses Monte Carlo simulations to explain experimental asymmetries in solute migration.

Findings

Results align with experimental observations of asymmetry.

The model demonstrates flux rectification as a key mechanism.

Approach is applicable to various transport scenarios across interfaces.

Abstract

Recent laboratory experiments on solute migration in composite porous columns have shown an asymmetry in the solute arrival time upon reversal of the flow direction, which is not explained by current paradigms of transport. In this work, we propose a definition for the solute flux across sharp interfaces and explore the underlying microscopic particle dynamics by applying Monte Carlo simulation. Our results are consistent with previous experimental findings and explain the observed transport asymmetry. An interpretation of the proposed physical mechanism in terms of a flux rectification is also provided. The approach is quite general and can be extended to other situations involving transport across sharp interfaces.