An efficient solver for the equations of resistive MHD with spatially-varying resistivity

We regularize the variable coefficient Helmholtz equations arising from implicit time discretizations for resistive MHD, in a way that leads to a symmetric positive-definite system uniformly in the time step. Standard centered-difference discretizations in space of the resulting PDE leads to a method that is second-order accurate, and that can be used with multigrid iteration to obtain efficient solvers. (C) 2008 Published by Elsevier Inc.