Adaptive-grid simulation of groundwater flow in heterogeneous aquifers

The prediction of contaminant transport in porous media requires the comput ation of the flow velocity. This work presents a methodology for high-accur acy computation of flow in a heterogeneous isotropic formation, employing a dual-flow formulation and adaptive gridding. The dual equations, describin g the hydraulic head and the streamfunction, are numerically solved through finite element approximations. The application of classic finite-element m ethods requires a rather large number of nodes to represent suitably the fl ow in high-contrast formations. We present a mesh-adaptive approach that en hances the accuracy of the numerical flow solution for a given computationa l effort. We rely on an a posteriori error estimator to identify areas wher e refinements of the finite element mesh are needed or unrefinements are ac ceptable. We also demonstrate through numerical experiments that the develo ped methodology efficiently enhances accuracy through successive mesh adapt ation. (C) 1999 Elsevier Science Ltd. All rights reserved.