An alternating direction galerkin technique for simulation of contaminant transport in complex groundwater systems

Abstract

A general contaminant transport simulation technique based on a Galerkin finite element representation in space and an alternating direction time‐stepping scheme is developed. The formulation, which is in terms of natural coordinates following the principal directions of hydraulic conductivity of the medium, decouples the spatial components of the equations, leading to tridiagonal matrices. The numerical accuracy can be easily controlled in each principal direction through the well‐established Peclet and Courant numbers. Results are found to be comparable to those from the classic finite element scheme, but the cost of computation is generally much less because the computational effort varies only linearly with the grid size. The technique is thus well suited for transport simulations with complex layered anisotropic groundwater systems requiring large and detailed grids.