Nonlinear magnetohydrodynamics simulation using highorder finite elements
Abstract
A conforming representation composed of 2D finite elements and finite Fourier series is applied to 3D nonlinear nonideal magnetohydrodynamics using a semiimplicit timeadvance. The selfadjoint semiimplicit operator and variational approach to spatial discretization are synergistic and enable simulation in the extremely stiff conditions found in high temperature plasmas without sacrificing the geometric flexibility needed for modeling laboratory experiments. Growth rates for resistive tearing modes with experimentally relevant Lundquist number are computed accurately with timesteps that are large with respect to the global Alfvén time and moderate spatial resolution when the finite elements have basis functions of polynomial degree (p) two or larger. An error diffusion method controls the generation of magnetic divergence error. Convergence studies show that this approach is effective for continuous basis functions with p⩾2, where the number of test functions for the divergence control terms is less than the number of degrees of freedom in the expansion for vector fields. Anisotropic thermal conduction at realistic ratios of parallel to perpendicular conductivity ( χ_{∥}/ χ_{⊥}) is computed accurately with p⩾3 without mesh alignment. A simulation of tearingmode evolution for a shaped toroidal tokamak equilibrium demonstrates the effectiveness of the algorithm in nonlinear conditions, and its results are used to verify the accuracy of the numerical anisotropic thermal conduction in 3D magnetic topologies.
 Publication:

Journal of Computational Physics
 Pub Date:
 March 2004
 DOI:
 10.1016/j.jcp.2003.10.004
 Bibcode:
 2004JCoPh.195..355S