Extended Magnetohydrodynamics in the FLASH Code

The FLASH code’s extended magnetohydrodynamic (MHD) capabilities have been greatly expanded recently. Improvements have been made to the Biermann battery and Hall terms in the induction equation, and several transport processes have been added to the code including anisotropic thermal conductivity, anisotropic magnetic resistivity, and thermoelectric effects. The implicit thermal diffusion solver was adapted to handle magnetic field dependent anisotropic conduction terms, while the implicit magnetic diffusion solver is a separate, new implementation. Seebeck, Righi–Leduc, and Nernst thermoelectric effects are solved with a flux-based explicit method. New resistivity and thermoelectric transport coefficients resulting from work with the Fokker–Planck code OSHUN (J. R. Davies et al., Phys. Plasmas 28, 012305 (2021)) have been incorporated into FLASH, and new thermal conductivity coefficients were also added (J.-Y. Ji and E. D. Held, Phys. Plasmas 20, 042114 (2013)). These new implementations enhance FLASH’s ability to model important magnetized plasma phenomena and problems such as Z-pinches.