User's manual for MGMHD: A multigrid three-dimensional computer code for the analysis of magnetohydrodynamic generators and diffusers

The Multigrid Magnetohydrodynamic (MGMHD) computer code is an updated and improved version of the single-grid Three-Dimensional Magnetohydrodynamic (TDMHD) code developed at Argonne National Laboratory in 1982 for the analysis of magnetohydrodynamic generators and diffusers. The new code retains the TDMHD formulation of three-dimensional partial differential equations for flow and electrical fields but incorporates an advanced multigrid solution algorithm. The magnetohydrodynamic equation set comprises the mass continuity equation, three momentum equations, the energy equation, two turbulence equations, and Maxwell's electrical equations. Turbulence is represented by a two-equation model in which partial differential equations are solved for the turbulence energy and its dissipation rate. Two unique features are provided in the MGMHD code: (1) a full approximation storage (FAS), block implicit multigrid, finite-difference solution procedure for the cross-stream hydrodynamic equations, and (2) an FAS multigrid finite-difference solution procedure for the cross-stream electrical potential equations. Detailed descriptions of the equations, solution procedures, options available to the user, and input instructions are presented. Numerical solutions of three sample problems (two Faraday generators and a diagonally connected generator) are discussed. For two of the problems, the multigrid and single-grid codes are compared in terms of computational speed and solution accuracy. 30 refs., 48 figs., 13more » tabs.« less