[FLASH-USERS] combining MHD and thermal conduction

[Slavin, Jonathan]

Hi all,

I've been trying to do supernova remnant evolution runs that include
electron thermal conduction and MHD using the unsplit staggered mesh unit.
I can do runs that include either electron thermal conduction or MHD but
when I try to combine them I get a rapid (after 43 steps) failure with:
 [gr_hypreSolve]: Ok ierr=0, component=0, converged=T, |initial
RHS|^2=3.6549+240, num_iterations=1, final_res_norm=NaN

so a nonconvergence related to thermal conduction, I believe.

Of course ideally one would use anisotropic thermal conduction (which has
been discussed previously on this list), but as an approximation I was
going to use a reduced conductivity to see what sort of results I got. I
was not expecting this sort of failure, especially so quickly.

I tried reducing the conductivity further and found that only by reducing
it by many orders of magnitude (~8) was I able to get runs that didn't
crash.  In those cases then there is essentially no conduction.  I also
tried a slow turn on of thermal conduction and that didn't work either.
I'm baffled about why I should get such failures.  It made me wonder if
there is some numerical way that the implementations of thermal conduction
and MHD interfere with each other.

Any help on this would be appreciated.

Regards,
Jon

-- 
________________________________________________________
Jonathan D. Slavin                 Harvard-Smithsonian CfA
jslavin at cfa.harvard.edu       60 Garden Street, MS 83
phone: (617) 496-7981       Cambridge, MA 02138-1516
cell: (781) 363-0035             USA
________________________________________________________
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