Three-Dimensional Finite-Volume ELLAM Implementation
COLORADO UNIV AT DENVER
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A three-dimensional finite-volume Eulerian-Lagrangian Localized Adjoint Method ELLAM has been developed, tested, and successfully implemented as part of the U.S. Geological Survey USGS MODFLOWMOC3D ground-water modeling package. The USGS ELLAM code simulates solute transport in ground water for a single dissolved constituent subject to advective transport, hydrodynamic dispersion including mechanical dispersion and diffusion, mixing from fluid sources, and simple chemical reactions including linear sorption and decay. The implementation conserves mass locally and globally. This ELLAM algorithm incorporates an implicit-in-time, finite-difference approximation for the dispersive and sourcesink terms, allowing large transport time increments to be used for greater efficiency. It uses a forward tracking approach to move mass to the new time level, distributing mass among destination cells using approximate characteristic functions. Numerous test cases indicate that the method can usually yield excellent results, even if relatively few transport time steps are used, although the quality of the results is problem dependent.
- Numerical Mathematics
- Fluid Mechanics