Abstract

The accurate description of transport of charged chemical species through porous media needs to include electrostatic interactions. While solute transport models have pursued the incorporation of electrostatic coupling effects, efforts have been primarily focused on Eulerian formulations of transport. Particle-based models provide an alternative approach with known advantages for simulating solute transport in porous media. However, electrostatic coupling effects are generally not considered, hence limiting the applicability of particle-based formulations to problems of multispecies ionic solute transport. This work presents a Random Walk Particle Tracking (RWPT) formulation that incorporates electrostatic coupling effects while calculating the displacement of solute particles. The formulation is based on an equivalent Fokker–Planck form of the Nernst–Planck-based transport equation that allows to determine the nonlinear transport coefficients that effectively incorporate electrostatic coupling in the particles’ displacements. The simulation approach is generalized, enabling the use of the RWPT method for simulating problems of multispecies ionic solute transport through homogeneous and heterogeneous porous media. Numerical simulations making use of the proposed formulation are benchmarked at different scales with experimental data and with known Eulerian solutions to problems of transport with electrostatic coupling, with results supporting the validity of the particle-based simulation approach.