COMPRESSIBLE LINEAR AND NONLINEAR RESISTIVE MHD CALCULATIONS IN TOROIDAL GEOMETRY

A formalism has been developed and incorporated in the computer code FAR to solve the magnetohydrodynamic (MHD) equations compressibly or incompressibly for either ideal or resistive modes. A linear subset or the full nonlinear set of equations can be solved, in toroidal geometry, with no ordering assumptions. Significant features of the formalism include (1) the addition of compressibility by adding two equations to a basic incompressible set, (2) the ability of the code to converge very rapidly for linear calculations, and (3) the use of a diffusive term in the evaluation of the compressible part of the velocity. This term damps the short-wavelength waves and allows a time step size which is comparable to that needed for incompressible simulations. © 1990.