[Users] Unexpected Hamiltonian constraint violation from refinement when using CCZ4

[Peter Diener]

Hi Kenneth,

It is expected that the mesh refinement boundaries will reflect 
Hamiltonian constraint violations. From what you have provided us, it is 
not clear whether the level of constraint violations that you see is a 
cause of concern. You specifically mention CCZ4, but have you tried with 
BSSN? Does the constraint violations look better, the same, or worse with 
BSSN?

It is also possible that an issue like this might be caused by some other 
problem potentially related to parameter settings, so in order to 
investigate this can you provide your thornlist and parameter file?

Cheers,

   Peter

On Sun, 4 Jul 2021, CHEN, Kenneth wrote:

> While using CCZ4 to simulate a single star, the Hamiltonian constraint
> violation initially came from the star surface as expected, but after some
> time, the violation was dominated by areas near corners of refinement levels
> (by Carpet) as shown in following figures, which were strange. Any
> suggestions?
> 
> Thanks and regards,
> KZ
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