[FLASH-USERS] [EXT] Re: question about radslab

[Youssef Abouhussien]

Hi Eddie,


Yes, thank you. The radiation source used in my experiment has a defined
temperature, but due to geometric effects, some photons are lost, resulting
in lower intensity reaching the target compared to the emitted radiation.
My objective is to reduce the energy deposition accordingly without
altering the source's radiation temperature, as changing the temperature
would produce a different energy deposition profile within the target. For
instance, photons from a 1 keV blackbody source penetrate deeper into the
target than photons from a 0.1 keV source. so changing urad() would
basically change the energy flux for that group but transport and
absorption would stay the same since it's wavelength dependant. Does that
make sense?


Regards,
Youssef


*------------------------------------------------------------------------------------------------------*
*Youssef Abouhussien*
*Research Assistant*
*Doctoral Student*
Virginia Commonwealth University
Dept. of Mechanical and Nuclear Engineering


On Wed, Jan 8, 2025 at 7:36 PM Hansen, Eddie <ehansen at pas.rochester.edu>
wrote:

> I’m not sure exactly what you’re trying to accomplish. Multi-group
> radiation transport is not independent of absorption or emission.
> Transport, absorption, and emission are all solved simultaneously per
> radiation energy group.
>
>
>
> Changing urad_tot in that routine won’t actually do anything since that
> variable is not actually passed out of the subroutine. The important one is
> urad() which is the radiation energy density per group. If you want to
> change the relationship between energy density U and T, then that’s more
> complicated…
>
>
>
> You would make changes in RadTrans_mgdUFromT to make the Dirichlet BC work
> the way you want it to, but you would also have to make corresponding
> changes in RadTrans.F90 to make the emission term consistent.
>
>
>
> --
>
> Eddie Hansen
>
> Applications Group Leader
>
> Flash Center for Computational Science
>
>
>
>
>
> *From: *Youssef Abouhussien <abouhussieny at vcu.edu>
> *Date: *Wednesday, January 8, 2025 at 7:10 PM
> *To: *Hansen, Eddie <ehansen at pas.rochester.edu>
> *Cc: *flash-users at flash.rochester.edu <flash-users at flash.rochester.edu>
> *Subject: *[EXT] Re: [FLASH-USERS] question about radslab
>
> Hi Eddie,
>
>
>
> Thank you for your email. I still want the radiation transport (hence
> wavelengths of the photons) to be carried out at a specific temperature. If
> I modified "urad_tot = urad_tot + urad(g)" from  RadTrans_mgdUFromT.90
> file and multiplied it by a constant to decrease the energy deposited to
> match the intensity i have in mind; would that work? Thanks.
>
>
>
> Regards,
>
> Youssef
>
>
>
>
>
>
> *------------------------------------------------------------------------------------------------------*
>
> *Youssef Abouhussien*
>
> *Research Assistant*
>
> *Doctoral Student*
>
> Virginia Commonwealth University
>
> Dept. of Mechanical and Nuclear Engineering
>
>
>
>
>
> On Wed, Jan 8, 2025 at 6:58 PM Hansen, Eddie <ehansen at pas.rochester.edu>
> wrote:
>
> Hi Youssef,
>
>
>
> The BC for RadSlab is not spatially-varying; it is just a single radiation
> temperature along the entire Yl boundary (the “dirichlet” boundary). There
> are runtime parameters that control the value of that temperature and some
> time-dependence, which are used in Simulation_adjustEvolution.
>
>
>
> If you have a specific intensity in mind, then you’d have to calculate
> what temperature that would be (e.g., I ~ T^4 for a blackbody).
>
>
>
> --
>
> Eddie Hansen
>
> Applications Group Leader
>
> Flash Center for Computational Science
>
>
>
>
>
> *From: *flash-users <flash-users-bounces at flash.rochester.edu> on behalf
> of Youssef Abouhussien <abouhussieny at vcu.edu>
> *Date: *Saturday, January 4, 2025 at 4:31 PM
> *To: *flash-users at flash.rochester.edu <flash-users at flash.rochester.edu>
> *Subject: *[FLASH-USERS] question about radslab
>
> Hi flash users,
>
>
>
> In RadSlab example for X-rays ablation, how can you specify the intensity?
> usually for blackbody source it's specified by the radiation temperature
> (cant change that for radiation transport purposes) and distance from
> target (for a point source) .
>
>
>
> Also i cant tell where the location of the source or shape (planar, point
> etc ) .
>
>
>
> thanks.
>
>
>
> Regards,
>
> Youssef
>
>
>
>
>
>
> *------------------------------------------------------------------------------------------------------*
>
> *Youssef Abouhussien*
>
> *Research Assistant*
>
> *Doctoral Student*
>
> Virginia Commonwealth University
>
> Dept. of Mechanical and Nuclear Engineering
>
>
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