[FLASH-USERS] fullaniso magnetic diffusion in the ZPinch example problem

[Hansen, Eddie]

Hi Heath,

It’s possible that there is a bug in the implicit solver. We have some significant updates coming for implicit magnetic diffusion in FLASH 4.8, but only for the ‘parallel’ or ‘perpendicular’ forms. We won’t be supporting implicit diffusion for the ‘fullaniso’ form just yet. You would need to use the explicit solver for that.

--
Eddie Hansen
Applications Group Leader
Flash Center for Computational Science


From: flash-users <flash-users-bounces at flash.rochester.edu> on behalf of Heath LeFevre <hjlefe at umich.edu>
Date: Tuesday, March 19, 2024 at 6:19 PM
To: flash-users at flash.rochester.edu <flash-users at flash.rochester.edu>
Subject: [FLASH-USERS] fullaniso magnetic diffusion in the ZPinch example problem
Hello,

I am trying to use the anisotropic magnetic resistivity in the ZPinch example problem. When I change resistivityForm to "fullaniso", the magnetic fields, and magnetic energy, go to zero. When resistivityForm is "perpendicular" there is heating and magnetic fields generated from the current.dat input file.

I changed the problem to 2D, so that having parallel and perpendicular terms make sense. I am using a uniform grid and the implicit solver. I attached my flash.par file, the log file, and the .dat file.

I read sections 18.1.6 and 14.3.5.3 of the manual, but I can't see what I'm doing wrong. It seems like changing from "perpendicular" to "fullaniso" should be all that is necessary to add the terms when solving the equations on a uniform grid. I also looked through the diff_advanceMag.F90 and DaviesWen MagneticResistivity_fullState.F90 files to see if there was an issue, but I couldn't find anything.

Does the problem have to do with using the implicit solver?

I would be very happy to hear suggestions from folks who have had success with this.

Thanks,
Heath
--
Heath LeFevre
He/Him/His
NSF ASCEND Postdoctoral Fellow
University of Michigan | Nuclear Engineering and Radiological Sciences
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