HIGH-ACCURACY ROBUST GROUNDWATER FLOW AND TRANSPORT CODES FOR ENVIRONMENTAL ENGINEERING

Computational algorithms and codes will be tailored specifically to the Air Force's needs in groundwater flow and pollutant transport as required in Environmental Engineering. The project will build heavily on previous and ongoing Ecodynamics work for Sandia Laboratories on the Waste Isolation Pilot Plant (WIPP) project and on proposed work for the U.S. Army Waterways Experiment Station. Robust, efficient, high-accuracy algorithms embodied in user-friendly codes will be developed for 2-D and 3-D time-dependent flows, including single phase miscible flows, multi-phase flows, NAPL, and DNAPL, and saturated and unsaturated (vadose-zone) conditions. Algorithmic innovations (even in Phase I) will include facilitation of grid convergence tests in multiple domains; automatic error estimation; correct treatment of transmissivity factors for unconfined aquifers; multigrid algorithms; a convenient formulation of variable density flow equations in terms of freshwater head; boundary-fitted coordinates; temporal high-order particle tracking; efficient, accurate and robust calculation of contaminant transport (advection, dispersion and diffusion) in (possibly) fractured porous media, and up-scaling of properties in strongly heterogeneous media. The codes will be designed for modern workstations with the highest standards of verification and Quality Assurance. Installation and tutorials will be provided to Tyndall AFB.