MS-VMS

MS-VMS DESCRIPTION

	Groundwater Pathline and Velocity Vector Plots

	Introduction to MS-VMS MS-VMS Applications MS-VMS Capabilities Input and Grid Construction MS-VMS Visualization MS-VMS Animation MODFLOW-SURFACT MS-VMS Requirements

INTRODUCTION TO MS-VMS MS-VMS is a comprehensive MODFLOW-based ground-water flow and contaminant transport modeling system. We believe that MS-VMS sets the highest standard for ground-water modeling in the industry. The USGS modular ground-water flow model, MODFLOW, is the most widely-used ground-water flow model in the world. But in its original form, MODFLOW has certain limitations and cannot be used to simulate some complex problems encountered regularly by modelers, hydrogeologists, and engineers in the field. MS-VMS APPLICATIONS Problems involving water withdrawal management from wells or wellfields. Problems involving rapid and large fluctuations of the water table. Problems involving unconfined recharge and seepage face conditions. Problems involving active or abandoned wells connecting multiple aquifers. Problems involving evaluation of pumping and tracer test data to determine hydraulic and transport properties of formations. Problems involving near field and far field simulations of ground-water flow and radionuclide transport. Problems involving contaminant and remedial investigations for contaminated sites including pump and treat systems, activated carbon barrier systems, bioremediation, and natural attenuation. MS-VMS CAPABILITIES Fully and variably-saturated flow modeling Parent and transformation product transport modeling Migration pathline and capture zone delineation Interactive input preparation and grid construction Visualization of modeling results in two and three dimensions

Contaminant Plume

Water Saturation (yellow indicates seepage face)

INTERACTIVE INPUT PREPARATION AND GRID CONSTRUCTION MS-VMS simplifies the cumbersome process of grid generation and preparation of data files through an interactive, easy-to-use graphical interface, Groundwater Vistas. The comprehensive mesh generator in Groundwater Vistas rapidly provides 2-D and 3-D finite-difference grids, thereby completely eliminating the tedium of model input preparation. The interface includes additional features such as importing AutoCAD DXF image files to facilitate the determination of the model boundaries. It also provides graphical input of pumping and observation well data. MS-VMS VISUALIZATION MS-VMS provides complete 2-D and 3-D visualization capabilities. Its Graphical User Interface, Groundwater Vistas, offers 2-D input and output visualization both in plan and cross-sectional views including contour plots, pathlines, and velocity vectors. Through TECPLOT, MS-VMS offers state-of-the-art 3-D visualization and animation. TECPLOT vividly depicts piezometric surfaces, pathlines and velocity vectors, and isosurfaces of contaminant plumes. MS-VMS ANIMATION Three-dimensional animation is the most effective way to observe the changes in parameters such as head and contaminant concentrations in a transient simulation. TECPLOT generates 2-D and 3-D animation sequences depicting changes in head, drawdown, and contaminant concentration with time. MODFLOW-SURFACT MODFLOW-SURFACT forms the nucleus of MS-VMS. Recognizing that few contaminant transport codes compatible with MODFLOW are available, new transport modules were developed and integrated into MODFLOW-SURFACT. The new transport modeling features include: Advective-dispersive transport of up to five species. Linear/non-linear retardation. First-order biochemical degradation in soil and/or water including generation of transformation products. MODFLOW-SURFACT overcomes several limitations of other available transport counterparts of the MODFLOW code. These limitations concern mass balance problems, excessive numerical dispersion and/or oscillations, and the implicit assumption of negligible impact of transient flow storage effects on transport. MODFLOW-SURFACT utilizes robust and efficient flux limiting transport schemes with Total Variation Diminishing (TVD) properties. These TVD schemes are not only mass-conservative but also are capable of accurately simulating steep concentration fronts. They are used in conjunction with an adaptive time-stepping procedure. For the sake of completeness, MODFLOW-SURFACT also offers standard finite-difference schemes including upstream, central, and combined central-upstream differencing with the Crank-Nicholson or fully-implicit time stepping. All schemes used in MODFLOW-SURFACT are strictly mass conservative producing numerical solutions with negligible mass balance errors. Input preparation for MODFLOW-SURFACT is straightforward and follows the MODFLOW format structure. Transport simulations make use of all MODFLOW data sets, and duplication of these data is eliminated. An additional data set including all transport parameters is required, and boundary conditions are implemented easily through the MODFLOW boundary data sets. MODFLOW-SURFACT ATTRIBUTES Handling of complete desaturation and resaturation of grid blocks. Accurate delineation and tracking of water table position taking into account flow in the unsaturated zone, delayed yield, and vertical flow components. Axisymmetric flow simulation option. Automatic and correct apportioning of the total flow rate of a multi-layer well to the well nodes. Accommodation of wellbore storage and overpumped wells. Handling of non-ponding or prescribed ponding recharge conditions. Handling of seepage face boundary conditions. Adaptive time-stepping schemes with automatic generation and control of time steps. Better organization and control of simulation output. Robust and efficient PCG matrix solution option. Comprehensive capability to perform groundwater flow and contaminant transport simulations using dynamic allocation of computer memory. Furthermore, the use of MODFLOW as a basis provides quick learning for MODFLOW users who require contaminant transport simulation capabilities. Rigorous solution of the primitive form of the transport equation while maintaining full compatibility with MODFLOW and all of its simulation options. Other MODFLOW-based transport codes neglect transient flow storage effects caused by factors such as compressibility and transient water-table and pumping conditions that lead to drainage and rewetting of grid cells. Such assumptions may result in unrealistic transport simulations. Handling of transport of contaminants with transformation (daughter) products taking into account first-order biochemical degradation or radioactive chain decay with linear or nonlinear equilibrium sorption. Availability of axisymmetric flow and transport analysis options. These options allow the user to obtain highly efficient analyses of aquifer tests, single-well tracer tests, and contaminant transport scenarios involving well injection and pumping. Accurate, robust, and efficient mass-conservative transport solution schemes. These schemes are seamlessly integrated into MODFLOW-SURFACT and are suitable for simulations of site-specific field characterization and remediation problems on microcomputers. Consistent transport numerical solution options. One option uses a standard upstream weighting scheme that is highly efficient but only first-order accurate. The second option uses the more computationally demanding, highly accurate TVD scheme with the van Leer flux limiter. Given certain requirements for numerical accuracy and computation speed, the user may readily choose a suitable option. MS-VMS Requirements: PC 486/Pentium with 16 MB RAM and Microsoft Windows 3.0 or later.

Τελευταία Ενημέρωση 27 Ιουλίου 2004 - Last Revised on July 27th 2004
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