WhiskyRMHD solves the general-relativistic resistive magnetohydrodynamics (RMHD) equations. The numerical method adopted exploits the properties of implicit- explicit Runge-Kutta numerical schemes to treat the stiff terms that appear in the equations for large electrical conductivities.
For details see:
K. Dionysopoulou, D. Alic, C. Palenzuela, L. Rezzolla, and B. Giacomazzo, “General-relativistic resistive magnetohydrodynamics in three dimensions: Formulation and tests“, Physical Review D 88, 044020 (2013)