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MAGNUM2D was developed to analyze thermally driven fluid motion in the deep basalts below the Paco Basin at the Westinghouse Hanford Site. Has been used in the Basalt Waste Isolation Project to simulate nonisothermal groundwater flow in a heterogeneous anisotropic medium and heat transport in a water-rock system near a high level nuclear waste repository. Allows three representations of the hydrogeologic system: an equivalent porous continuum, a system of discrete, unfilled, and inter- connecting fractures separated by impervious rock mass, and a low permeability porous continuum with several discrete, unfilled fractures traversing the medium. The calculations assume local thermodynamic equilibrium between the rock and groundwater, non- isothermal Darcian flow in the continuum portions of the rock, and nonisothermal Poiseuille flow in discrete unfilled fractures. In addition, the code accounts for thermal loading within the elements, zero normal gradient and fixed boundary conditions for both temperature and hydraulic head, and simulation of the temperature and flow independently. The Q2DGEOM preprocessor was developed to generate, modify, plot and verify quadratic two dimensional finite element geometries. The BCGEN preprocessor generates the boundary conditions for head and temperature and ICGEN generates the initial conditions. The GRIDDER postprocessor interpolates nonregularly spaced nodal flow and temperature data onto a regular rectangular grid. CONTOUR plots and labels contour lines for a function of two variables and PARAM plots cross sections and time histories for a function of time and one or two spatial variables. NPRINT generates data tables that display the data along horizontal or vertical cross sections. VELPLT differentiates the hydraulic head and buoyancy data and plots the velocity vectors. The PATH postprocessor plots flow paths and computes the corresponding travel times.
MAGNUM2D is a two-dimensional finite element numerical model for transient or steady state analysis of coupled processes of advective and conductive heat transfers in a porous continuum and buoyancy driven groundwater flow in a saturated, fractured, porous medium. The governing equations consist of a set of coupled, quasilinear partial differential equations that are based on the physical laws of fluid continuity and conservation of momentum and energy. The solutions are based on a Galerkin finite element scheme, using a block diagonal frontal solution technique. The computational network consists of both quadrilateral and triangular elements to model the continuum regions of the spatial domain, and line elements to represent the discrete fractures within the domain. A Newton-Raphson algorithm is embedded in the Galerkin functional to formulate the problems in terms of the incremental changes in the dependent variables. This method allows substantial flexibility in discretization of the spatial domain. The flow equations are solved simultaneously, and the flow and heat transfer equations are solved in alternating sequence. The simulation domain may be modeled in two Cartesian dimensions or in a radial coordinate system that is symmetric around the vertical axis.
Maxima of 3000 nodes, 960 elements, 225 heat source elements, 50 thermal load points, 25 material types, 25 time intervals, 5 binary input files. The number of nodes define the element: 8 nodes specify a quadrilateral, 6 nodes specify a triangular shape and 3 nodes specify a linear element. The element aspect ratio affects the accuracy of the results and should be kept at a value below 100. The reference temperature must be between 0.0 and 300.0 degrees C.
MAGNUM2D requires the proprietary CA-DISSPLA graphics library (see http://www.gaeinc.com) to utilize the graphics post processor; this program is not included.
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R.G. Baca, B. Sagar, and D.W. Langford, MAGNUM2D - A Finite Element Model for Coupled Heat Transport and Ground Water Flow in Fractured Porous Media: Mathematical Theory, Numerical Techniques, and Computational Test WHC-EP-0023 (December 1987).
L.L. Eyler and M.J. Budden, Verification and Benchmarking of MAGNUM2D - A Finite Element Computer Code for Flow and Heat Transfer in Fractured Porous Media PNL-5237 (March 1985).
D. Langford, MAGNUM2D Computer Code: Requirements Document Westinghouse Hanford Report (August 28, 1987).
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Keywords: finite element method, flow models, fluid flow, ground water, heat transfer, hydraulics, partial differential equations, porous materials, radioactive waste storage, radionuclide migration, temperature distribution.