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Meshless Local Strong Form-based Method for Transport Simulation of Nonlinearly Adsorbing Solutes in a Highly Heterogeneous Confined Aquifer
Journal
Water Resources Management
ISSN
09204741
Date Issued
2022-03-01
Author(s)
Anshuman, Aatish
Eldho, T. I.
Abstract
A meshless simulation model based on the radial point collocation method (RPCM) is developed in this study to simulate contaminant transport in heterogeneous aquifers with nonlinear adsorption. The nonlinear adsorption is represented using popularly used Langmuir’s isotherm. The nonlinear governing equation of the contaminant transport is solved utilizing linearization through timesteps. The directional derivatives of hydraulic conductivity field through vectorization are used to simulate flow in highly heterogeneous aquifers. Multiquadrics radial basis functions (MQ-RBF) are used for the approximation of heads and concentrations and their gradients. The relevant equations are solved locally using the domain decomposition technique, which avoids the ill-conditioning issue associated with globally supported domains. The developed models are named RPCM-NA (for only transport) and RPCM-CNA (for coupled flow and transport). The RPCM-NA model is validated against semi-analytical solutions, and its advantages over the Finite Difference Method (FDM) are demonstrated. Two case studies are considered. The performance of the RPCM-CNA model is compared to that of FDM-based MODFLOW and MT3DMS models, with the maximum percentage error for head estimation being 0.25%. For contaminant transport simulation in the mobile and adsorbed phases, the maximum values of Normalized Mean Absolute Error obtained are 0.02 and 0.0385 respectively, showing the effectiveness of the proposed model.
Volume
36
Subjects