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|Title:||MT3DMS : a modular three-dimensional multispecies transport model for simulation of advection, dispersion, and chemical reactions of contaminants in groundwater systems; documentation and user’s guide|
|Authors:||University of Alabama. Department of Geological Sciences.|
Strategic Environmental Research and Development Program (U.S.)
Zheng, Chunmiao, 1962-
Wang, P. Patrick.
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: This manual describes the next generation of the modular three-dimensional transport model, MT3D, with significantly expanded capabilities, including the addition of (A.) a third-order total-variation-diminishing (TVD) scheme for solving the advection term that is mass conservative but does not introduce excessive numerical dispersion and artificial oscillation, (B.) an efficient iterative solver based on generalized conjugate gradient methods and the Lanczos/ORTHOMIN acceleration scheme to remove stability constraints on the transport time-step size, (C.) options for accommodating nonequilibrium sorption and dual-domain advection-diffusion mass transport, and (D.) a multicomponent program structure that can accommodate add-on reaction packages for modeling general biological and geochemical reactions. The new modular multispecies transport model, referred to as MT3DMS in this manual, is unique in that it includes the three major classes of transport solution techniques (i.e., the standard finite-difference method, the particle-tracking-based Eulerian-Lagrangian methods, and the higher-order finite-volume TVD method) in a single code. Since no single numerical technique has been effective for all transport conditions, the combination of these solution techniques, each having its own strengths and limitations, is believed to offer the best approach for solving the most wide-ranging transport problems with desired efficiency and accuracy. MT3DMS can be used to simulate changes in concentrations of miscible contaminants in groundwater considering advection, dispersion, diffusion, and some basic chemical reactions, with various types of boundary conditions and external sources or sinks. The basic chemical reactions included in the model are equilibrium-controlled or rate-limited linear or nonlinear sorption and first-order irreversible or reversible kinetic reactions. More sophisticated multispecies chemical reactions can be simulated by add-on reaction packages. MT3DMS can accommodate very general spatial discretization schemes and transport boundary conditions, including: (A.) confined, unconfined, or variably confined/unconfined aquifer layers, (B.) inclined model layers and variable cell thickness within the same layer, (C.) specified concentration or mass flux boundaries, and (D.) the solute transport effects of external hydraulic sources and sinks such as wells, drains, rivers, areal recharge, and evapotranspiration. MT3DMS is designed for use with any block-centered finite-difference flow model, such as the U.S. Geological Survey modular finite-difference groundwater flow model, MODFLOW, under the assumption of constant fluid density and full saturation. However, MT3DMS can also be coupled with a variably saturated or density-dependent flow model for simulation of transport under such conditions.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Contract Report|