[FLASH-USERS] combining MHD and thermal conduction

[ERNESTO ZURBRIGGEN]

Jon,

>I maybe should have mentioned that my runs have been in 2D (cylindrical).
So have you done such runs?
No, I have done runs just in cartesian coordinates.

>Also for the conduction, I'm using unsplit diffusion with electron thermal
conduction and power law conductivity.
Exactly.
You might
also be interested in saturated conduction, for this FLASH offered the
runtime parameter diff_eleFlMode.

>You mention being careful with split vs. unsplit diffusion, but you don't
say which one works - or >what that means to be careful.​

​ Or is it just that parameter setting addThermalFlux? I'll try >setting
that to False to see if that helps.
Sorry for not being clear. I wanted to say that I have set up
unsplit/MHD + Diffusion/unsplit
or
unsplit/MHD + Diffusion/split,
obtaining good results with both but I'm not sure if the second option is
completely compatible. In both cases you have to set addThermalFlux=false.

In regards to what Klaus mentioned,
>This indicated that the variable you are trying to diffuse - temperature, I
assume - is extremely >high already on entry to the diffusion solver. This
could be either from previous calls of the >diffusion solver, or from
something else having gone wrong in previous time steps.
at least in my case, the above units' setup have worked well for
temperatures as high as 20MK and densities of the order of 1e-15 gr*cm(-3).


>To answer your question, I'm not using super-time-stepping.  Didn't seem
necessary since with Crank Nicholson diffusion you have unconditional
stability.  So I haven't looked into how to use that.
Even in this situation I have turned on STS obtaining speed up and good
results.
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