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A Modular Three-Dimensional Flow and Transport Code
Software Developed by HydroSOLVE, Inc.
 Description
MODFLOWT is a version of MODFLOW that includes modules for simulating three-dimensional
contaminant transport.
Developed by Glenn M. Duffield of HydroSOLVE, Inc. and
GeoTrans, MODFLOWT solves the advective-dispersive transport equation using a
fully-implicit finite-difference technique with full expansion of the dispersion tensor.
Features
MODFLOWT is fully compatible with previous versions of MODFLOW.
The program offers an extensive array of solution options for simulating contaminant
transport in groundwater.
 | Advective-dispersive transport with adsorption and first-order decay |
| Central differencing and upstream weighting options for advective terms
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| Fully implicit (backward-in-time) and Crank-Nicolson (central-in-time) options for the
time derivative |
| Longitudinal and transverse dispersivities plus optional "vertical"
dispersivity |
| Optional expansion of cross products in dispersion tensor |
| Decay chains for up to n-components |
| Spatially variable decay rates and retardation factors and variable porosity
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MODFLOWT provides a comprehensive suite of solvers for simulating groundwater flow and
solute transport.
| Choice of strongly implicit procedure (SIP), slice-successive overrelaxation (SSOR),
enhanced preconditioned conjugate gradient (PCG) and ORTHOMIN
(OMN) solvers for flow |
| Choice of slice-successive overrelaxation (SSOR) and ORTHOMIN
(OMN) solvers for transport |
MODFLOWT provides features designed for simulating real-world problems.
| Options for simulating transient transport with steady-state flow, transient flow or
successive periods of steady-state flow |
| Automatic time stepping with adaptive controls for transport |
| Restart capabilities for flow and transport simulations |
| Observation Well Package for
recording heads and concentration at observation nodes |
| Output files for recording concentrations and concentration changes in MODFLOW's
standard "head save" format |
| Output file for detailed mass budget history |
| Dynamic allocation of memory |
Solution Methods
MODFLOWT uses an implicit finite-difference discretization scheme for the numerical
solution of the partial differential equations for solute transport. Central differencing
and upstream weighting options are available for the solution of advective terms. In
addition, MODFLOWT offers fully implicit (backward-in-time) or Crank-Nicholson
(central-in-time) approximation options for the time derivative.
MODFLOWT provides a comprehensive suite of solvers for matrix solution. For flow, you
can choose from the Strongly Implicit Procedure (SIP), Preconditioned Conjugate Gradient
(PCG2), Slice Successive Overrelaxation (SSOR) and ORTHOMIN (OMN) solvers. For transport,
the available solvers are Slice Successive Overrelaxation and ORTHOMIN.
The
ORTHOMIN solver, developed
by HydroSOLVE, Inc., has advantages over traditional solvers available for MODFLOW.
When used for flow simulations, the ORTHOMIN solver functions as an enhanced version of
the preconditioned conjugate gradient method; however, coding improvements make the
ORTHOMIN solver faster and computationally more efficient than traditional PCG2!
Support
Support for MODFLOWT is provided by
Geotrans, Inc.
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