AN ADAPTIVE FINITE-ELEMENT MODEL FOR CALCULATING SUBSURFACE TRANSPORTOF CONTAMINANT

A finite-element method which incorporates mesh adaptation is used to calculate ground-water flow and pollutant transport. The formulation i s based on the equations for conservation of mass, Darcy's law for an anisotropic medium, and the time-dependent species transport equation. Modifications have been implemented to the finite-element formulation to enhance computational speed and reduce storage; Petrov-Galerkin we ighting of the advection terms provides numerical stability. An explic it time marching scheme is used to solve the transient equations. By u tilizing unstructured adaptive meshing, species concentration and loca tion of steep fronts are accurately resolved, even though one begins w ith a coarse mesh. The algorithm currently runs on PC and workstation class computers.