[FLASH-USERS] MHD blast problem in cylindrical symmetry

[Slavin, Jonathan]

Hi all,

I'm still trying to get my SNR in magnetized medium simulation to work, but
I decided to take a step back and see if the simplified example BlastBS
would work in cylindrical symmetry.  For that I needed to make a few small
changes in Simulation_data, Simulation_init, Simulation_initBlock and
Config wherein I needed to allow for a non-zero value for By0 in addition
to Bx0 since in cylindrical symmetry (R-Z) we want the z component of the
field to be non-zero and the r component to initially be zero (r maps to x,
z maps to y).  I accidentally used the 8-wave version of MHD the first time
(forgot to specify +usm to setup) and it worked fine.  When I used the USM
version of MHD though, it started out okay but then ran into a negative
computed dt:
Error message is [Hydro]: Computed dt is not positive! Aborting!
I assume that that is because the temperature becomes negative somehow.
Just before the error the printed dt_hydro suddenly drops.   Does anyone
have any idea why that might be?  Any suggestions for ways to avoid this?
One possibility might be to set a higher value for smallp and./or smlrho, I
guess.

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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