Meshfree radial point collocation-based coupled flow and transport model for simulation of multispecies linked first order reactions

Abstract

Mesh/grid-based methods such as the Finite element method (FEM) and Finite difference method (FDM) are extensively used for simulation of contaminant species transport in groundwater. However, these methods in their standard form are susceptible to instabilities such as oscillations and numerical dispersion in the solution. Further, due to the use of mesh/grid, these methods are also computationally expensive. In this study, a meshfree method named Radial point collocation method (RPCM) is demonstrated for simulating reactive transport involving linked first-order reactions in a coupled flow environment. Multiquadrics radial basis functions (MQ-RBF) are used for approximation of the state variables. The model uses local support domains which produce sparse matrix systems that efficiently deal with the ill-conditioning problem which generally occurs while using global support domains. The model developed is verified against the semi-analytical solutions and its performance is compared with FEM for case studies. It is observed that the model provides accurate solutions for the problems considered and also handles advective flow conditions better than FEM. The proposed model successfully simulates the fate of contaminants in linked chain reactions.