[FLASH-USERS] Radiative Flux in FLASH
David Montgomery
dsmont80 at gmail.com
Fri Jul 11 13:19:56 EDT 2025
HI Owen,
I’m a newbie too, but I ran across the following while learning about FLASH:
if you have 7 mgd groups, if you look at the “lasslab_hdf5_chk****” “check point” file that is force dumped, it contains ALL FLASH variables, in addition to the ones you requested to be plotted in the “plot_var” statements that are specified in the *.par file you’re using to set up.
There should be variables named r001, r002, r003, … r00N up to the number of MGD groups N, which are specific radiation energy in each group (ergs/g).
If you want those at each plot dump, you could declare them in the *.par file as “plt_var” like the other variables. Or you can specify the force dump time intervals by modifying:
### Checkpoint Options ###
checkpointFileIntervalTime = 1.0
checkpointFileIntervalStep = 1000
David Montgomery
> On Jul 11, 2025, at 9:58 AM, Owen Bardeen <owenbardeen at gmail.com> wrote:
>
> Just to provide some more context in case it's helpful:
>
> I am using FLASH version 4.7.1, with the LaserSlab module. I have 7 mgd groups, as outlined in my .par file:
> rt_useMGD = .true.
> rt_mgdNumGroups = 7
>
> It seems to me that FLASH must store information about radiation transfer in each group somewhere. I'm looking in FLASH4.7.1/source/physics/RadTrans/RadTransMain/MGD but it's not obvious to me where it's stored. It would be nice if I could just add it as a variable to flash.par to be included in the output files, but if I have to dig into the Fortran that's fine too.
>
> If someone could point me in the right direction it would be much appreciated.
>
> Thank you!
> Owen
>
> On Wed, Jul 9, 2025 at 3:30 PM Owen Bardeen <owenbardeen at gmail.com <mailto:owenbardeen at gmail.com>> wrote:
>> Hello all,
>> I’m currently working on a simulation involving radiative transport in a hot plasma using the FLASH code (v4.7.1). I’m interested in quantifying the radiative emission, with the capability of comparing radiative emission from different energy groups (0.1-1 eV, 1-10 eV, etc.).
>>
>> My question is: what is the best way to determine the total radiative output, as well as from one specific energy bin/group, from FLASH output?
>>
>> I’ve generated the necessary Propaceos opacity tables with a dedicated energy group covering just this narrow range.
>>
>> If anyone has experience extracting radiative output from individual bands in FLASH, I’d greatly appreciate your guidance.
>>
>> Thank you!
>>
>> Owen Bardeen
>>
>> University of California, San Diego
>>
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