Modelling Coupled Flow-Solute Transport in Porous Media using Smoothed Particle Hydrodynamics (SPH)

Subsurface contamination is often hazardous to human health and the environment. Understanding the coupled process of flow of water and contaminant (solute) transport in porous media is essential for assessing the extent, designing mitigation measures, and enhancing resilience against subsurface contamination. The present study develops a numerical framework based on the SPH method for modelling coupled flow-solute transport in threephase, non-deformable porous media. A generalized mathematical model describing the coupled process is arrived at based on the continuum mixture theory. The governing equations of the model are solved using a single-layer SPH framework for the first time. The developed numerical framework is validated against closedform solutions of one- and two-dimensional solute transport in porous media, semi-analytical solution of the Henry problem, and a laboratory-scale experiment of saltwater intrusion involving density-driven flow. Satisfactory agreement with the analytical, numerical, and experimental results indicates that the proposed SPH framework can be adopted for solving complex, field-scale problems involving the flow of water and solute transport in porous media. The present study also serves as the foundation for further research towards solving coupled flow-deformation-solute transport problems involving large deformations of porous media using the SPH method, which may prove challenging for mesh-based numerical techniques.