[FLASH-USERS] Numerical Effects in Spherical Coordinates

[Michiel Bustraan]

Dear all,?


I forgot to include the log file.

Unfortunately, I neglected to save the log file for this run.

However, I do have a log file from a previous simulation in the same setup.

The only difference is that I ran it with a different temperature, but the results were largely the same.


- Michiel

________________________________
From: flash-users-bounces at flash.uchicago.edu <flash-users-bounces at flash.uchicago.edu> on behalf of Michiel Bustraan <michiel.bustraan at astro.su.se>
Sent: Wednesday, March 22, 2017 2:10 PM
To: flash-users at flash.uchicago.edu
Subject: [FLASH-USERS] Numerical Effects in Spherical Coordinates


Dear FLASH Users,


I've been running 2D simulations of shocks in spherical simulations.

The initial conditions involve a high density around the origin.


I had to introduce random temperature fluctuations in the inner region to ensure refinement.

I started with quite a high level of refinement, and the maximum level of refinement decreases over time (from 10 layers to 5).


I've found that ripples appear in the inner portion of the domain, as well as larger numerical artifacts.

I think that these might either be due to:


- The initial temperature fluctuations I added, though I feel these would be too small (spatially) to cause all these issues.

- Could it be that the higher pressure region in the center, combined with the lower radial velocity, cause the gas to bounce off the inner boundary?

This might create ripples and internal shocks.


Either way, I'm not certain how to improve my results from here.

If anyone has had similar problems, I would greatly appreciate some advice.


The figures attached highlight my problem.


Kind Regards,

Michiel Bustraan
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