An unsplit, cell-centered Godunov method for ideal MHD

  • Authors:

  • Robert K. Crockett;Phillip Colella;Robert T. Fisher;Richard I. Klein;Christopher F. McKee

  • Affiliations:

  • Department of Physics, University of California, Berkeley, CA 94720, USA and Lawrence Livermore National Laboratory, Livermore CA 94551, USA;Lawrence Livermore National Laboratory, Livermore CA 94551, USA;Department of Astronomy, University of California, Berkeley, CA 94720, USA;Lawrence Berkeley National Laboratory, Berkeley CA, 94720, USA and Department of Astronomy, University of California, Berkeley, CA 94720, USA;Department of Physics, University of California, Berkeley, CA 94720, USA and Lawrence Berkeley National Laboratory, Berkeley CA, 94720, USA

  • Venue:
  • Journal of Computational Physics
  • Year:
  • 2005

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Abstract

We present a second-order Godunov algorithm for multidimensional, ideal MHD. Our algorithm is based on the unsplit formulation of Colella (J. Comput. Phys. 87, 1990), with all of the primary dependent variables centered at the same location. To properly represent the divergence-free condition of the magnetic fields, we apply a discrete projection to the intermediate values of the field at cell faces, and apply a filter to the primary dependent variables at the end of each time step. We test the method against a suite of linear and nonlinear tests to ascertain accuracy and stability of the scheme under a variety of conditions. The test suite includes rotated planar linear waves, MHD shock tube problems, low-beta flux tubes, and a magnetized rotor problem. For all of these cases, we observe that the algorithm is second-order accurate for smooth solutions, converges to the correct weak solution for problems involving shocks, and exhibits no evidence of instability or loss of accuracy due to the possible presence of non-solenoidal fields.