[FLASH-USERS] Pressure Fluctuations from AMR

[Michiel Bustraan]

Tomek,

Could you expand on the difference between what you call on-and-off and uniform refinement?
Do you mean that this wouldn't happen with a uniform resolution, because that is correct.
In the absence of refinement, the simulation runs normally.

- Michiel
________________________________________
From: flash-users-bounces at flash.uchicago.edu <flash-users-bounces at flash.uchicago.edu> on behalf of Tomasz Plewa <tplewa at fsu.edu>
Sent: Wednesday, September 13, 2017 7:12 PM
To: flash-users at flash.uchicago.edu
Subject: Re: [FLASH-USERS] Pressure Fluctuations from AMR

I bet on on-and-off refinement/derefinment. I would expect no such
features appear in uniformly refined models.

Tomek
--
On 09/12/17 08:25, Michiel Bustraan wrote:
>
> Dear FLASH users,
>
>
> I've been encountering a problem with AMR.
>
> The attached images show the issue.
>
> I always find sharp pressure fluctuations occuring near the origin,
> and this only happens with several layers of AMR.
>
> Since this region does not contain high velocities or pressures, it
> seems bizarre that this is happening.
>
>
> These simulations use spherical coordinates, 2D, and split PPM hydro.
>
>
> I originally ran the simulations without specialized grid refinement
> conditions, which led to worse pressure spikes.
>
> I was hoping that by layering the refinement (5 layers out to 2e15 cm,
> 4 layers to 4e15, etc.) using Grid_markRefineDerefine.F90,
>
> it would solve the issue. However, as you can see in the attached
> images, that has not been the case.
>
>
> Has anyone experienced something like this using AMR?
>
> Since the region is fairly flat (in density, pressure, and
> temperature), I am uncertain where these features could come from.
>
>
> Kind Regards,
>
> Michiel Bustraan
>