[FLASH-USERS] [EXT] boundary conditions and refinement

[Ernesto Zurbriggen]

Hi Thibault!

>>For my case, the density gradients in the white frame are big enough to
be identify by the AMR
Refinement is mainly determined by gradients and not by values, as exposed
by eq. 8.1 in user manual.

Play with "refine_cutoff" and "derefine_cutoff" is much easier than
properly set the “Grid_markRefineSpecialized” routine.

>>if *refine_var_1 = "dens"*, I tried *refine_cutoff_1 =1e-5* to blunder
the AMR for densities below 1e-5 g/cc but I >>haven't noticed any
>>consequences.
Default refine_cutoff value is 0.8. For smaller values you are saying
PARAMESH to be more sensible to refine.
I think you may want to set a larger value than default 0.8.

Derefine_cutoff default value is 0.2. For larger values PARAMESH is more
sensible to derefine.
So here you may also want to set larger values than 0.2.

Best regards!
Ernesto.







El sáb, 10 abr 2021 a las 14:35, Reyes, Adam (<adam.reyes at rochester.edu>)
escribió:

> Hi Thibault,
>
> You can make use of the routine “Grid_markRefineSpecialized” located in "source/Grid/GridMain/paramesh/“.
> See also the section in the users guide on Specialized Refinement Routines
> <http://flash.uchicago.edu/site/flashcode/user_support/flash4_ug_4p62/node59.html#SECTION05163000000000000000>
> .
>
> You’ll want to copy the routine “Grid_markRefineDerefine” to your
> simulation directory and add a call to “Grid_markRefineSpecialized” near
> the other specialized refinement routine calls. The “RECTANGLE” criterion
> should do what you want with the “lref” argument set to your desired
> refinement level for the region.
>
> Adam
>
>
> On Apr 10, 2021, at 6:32 AM, Thibault Goudal <
> thibault.goudal at u-bordeaux.fr> wrote:
>
> Hi everyone,
> I''ve been working on 2D FLASH simulations in cartesian geometry with a
> laser.
>
> <Capture1.PNG>
> On this density map in logarithm scale, a laser hits a modulated target
> (see the modulation at ~0.030cm) from the bottom at normal incidence.
> During the laser irradiation, the target is ablated and ejected through
> the pseudo vaccum (see the white frame).
>
> My question is: How could I tell FLASH to not refine the region framed?
>
> I noticed in the user guide and previous e-mails by the FLASH community
> that it exists AMR options such as "refine_cutoff " or "derefine_cutoff "
> which I think could solve my issue.
> I tried to play with it but I haven't see any effects on the refinement.
> For my case, the density gradients in the white frame are big enough to be
> identify by the AMR.
> However, the absolute density is quiet low so I guess I could use these
> informations to tell FLASH that under a certain value in density it should
> forget what are the gradients and not trigger the AMR refinement.
>
> if refine_var_1 = "dens", I tried refine_cutoff_1 =1e-5 to blunder the AMR
> for densities below 1e-5 g/cc but I haven't noticed any consequences.
>
> If you have any idea about how tune the AMR option to solve this kind of
> issue, let me know!
>
> Have a great week-end
>
> --
> Thibault Goudal
> PhD Student CEA
> CELIA CNRS UMR5107 laboratory
> +33664160842
> thibault.goudal at u-bordeaux.fr
>
>
>
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