[FLASH-USERS] Tabulated Eos + RadTrans

[Yannick de Jong]

Hi Markus,

The RadTrans_computeDt routine calls the EOS module with
MODE_DENS_TEMP_ELE, and while the 3T multitype EOS is designed to handle
electrons and ions separately, that specific input mode has not been
implemented. (though it would be straightforward to add)

You could try to modify the RadTrans_computeDt subroutine to use an
implemented mode that calculates both electron and ion properties (though
note this may be less performant). In
source/physics/RadTrans/RadTransMain/MGD/RadTrans_computeDt.F90, change:
`mode = MODE_DENS_TEMP_ELE` to: `mode = MODE_DENS_TEMP_GATHER`

Alternatively you can reduce your timestep manually, for example by setting
a dtmax in your par file.

Best,
Yannick de Jong

Ignition Computing | Software Engineer

E: ydejong at ignitioncomputing.com
W: ignitioncomputing.com



On Mon, 4 Aug 2025 at 14:35, Dr. Markus Nöth <markus.noeth at marvelfusion.com>
wrote:

>
>
> Dear flash team,
>
>
>
> I’m working on a modified version of the ZPinch setup. I’ve been
> experiencing oscillations in the temperature which vanishes when switching
> off RadTrans. That’s why I’ve switched on the runtime flag rt_computeDt =
> .true. in flash.par. This worked well as long as I was using an ideal gas
> law for electrons and ions. Now I’ve switched to tabulated eos and run into
> the following error
>
>
>
> Error message is [Eos] Unrecognized input mode given to Eos
>
>
>
> I’ve traced origin of the error to the Eos call in
>
> source/physics/RadTrans/RadTransMain/MGD/RadTrans_computeDt.
>
>
>
> The eos mode in this call is MODE_DENS_TEMP_ELE, which is not recognized
> by the select statement in line 495 in the file
>
> source/physics/Eos/EosMain/multiTemp/Multitype/Eos
>
>
>
> The error can be reproduced by compiling the standard magnetoHD/ZPinch
> example, after setting rt_computeDt = .true. in flash.par.
>
>
>
> Why does this happen? Is there a way to use both tabulated eos and
> rt_computeDT?
>
>
>
> Best,
>
> Markus
>
>
>
>
>
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> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> Dr. Markus Nöth
> Scientist
> +49 89 262023263
>
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