A nonlinear random walk approach to concentration-dependent contaminant transport in porous media

TL;DR

This paper introduces a nonlinear random walk model to simulate concentration-dependent contaminant transport in porous media, capturing non-Fickian behaviors and validated through experiments and Monte Carlo simulations.

Contribution

It presents a novel nonlinear random walk framework that couples concentration and velocity fields, advancing the modeling of dense contaminant plumes in porous media.

Findings

Model captures non-Fickian transport features.

Simulation results agree with experimental data.

Provides insights into concentration-dependent dynamics.

Abstract

We propose a nonlinear random walk model to describe the dynamics of dense contaminant plumes in porous media. A coupling between concentration and velocity fields is found, so that transport displays non-Fickian features. The qualitative behavior of the pollutant spatial profiles and moments is explored with the help of Monte Carlo simulation, within a Continuous Time Random Walk approach. Model outcomes are then compared with experimental measurements of variable-density contaminant transport in homogeneous and saturated vertical columns.