GGSD Program Details for MODFE

MODFE

Category	Groundwater flow (2D)
Publisher	US Geological Survey
Platform	UNIX, DG, Sun
Status	Public domain
Description	MODFE (MODular, Finite Element) program was developed to provide solutions to groundwater flow problems based on the governing equations that describe 2D and axisymmetric radial flow in porous media. Aquifer geometry, flow boundaries, and variations in hydraulic properties are represented by triangular elements or element sides in a finite element mesh. Time variations in hydraulic properties are represented by 1D elements. Linear coordinate functions are used to approximate variations in hydraulic properties within elements. The finite element matrix equations are solved by using either a direct symmetric Doolittle method of triangular decomposition or an iterative method that uses the modified, incomplete Cholesky, conjugate gradient method. The direct method can be efficient for small to medium sized problems (less than about 500 nodes), and the iterative method is generally more efficient for larger sized problems. Simulation capabilities and uses are: transient or steady state conditions; nonhomogeneous and anisotropic flow where directions of anisotropy change within the model region; vertical leakage from a semiconfining layer that contains laterally nonhomogeneous properties and elastic storage effects; point and areally distributed sources and sinks, specified head (Dirichlet); specified flow (Neumann); and head dependent (Cauchy type) boundary conditions; vertical cross-section and axisymmetric cylindrical flow; confined and unconfined (watertable) conditions; partial drying and resaturation of a watertable aquifer; conversion between confined and unconfined aquifer conditions; and nonlinear head dependent fluxes (for simulating line, point, or areally distributed sources and sinks). Aquifer stresses and boundary conditions can be changed on a time step basis, a stress period basis, or both. Hydraulic properties and boundary conditions can be input by zone.
Cost	Free on WWW
Data formats supported	None stated
Supplier in United States of America	International Ground Water Modeling Center
Supplier in United States of America	US Geological Survey