[ET Trac] #2648: Empty ApplyBCs call in LeanBSSNMoL

helvi witek trac-noreply at einsteintoolkit.org
Fri Jan 27 09:53:26 CST 2023


#2648: Empty ApplyBCs call in LeanBSSNMoL

 Reporter: Samuel Cupp
   Status: new
Milestone: 
  Version: 
     Type: bug
 Priority: major
Component: EinsteinToolkit thorn

Comment (by helvi witek):

> After ADM2BSSN one usually has to SYNC, extrapolate and apply symmetry boundary conditions \(possibly in a very specific order\) and the Gamma auxiliary variables of the BSSN system which involve derivatives so cannot be set in ghost zones and the boundary. Most others can be computed point by point, so that a missing SYNC \(missing for sure it seems\) will only show up a slight change in regions filled via prolongation \(but not in inter-processor ghosts or in restriction target region\).

@Roland: Ok, Let me add the relevant part of schedule.ccl:

```
schedule LeanBSSN_adm2bssn at CCTK_INITIAL after ADMBase_PostInitial
{
  LANG: Fortran
  OPTIONS: Local
   SYNC: gammat
} "Convert initial data into BSSN variables"

schedule GROUP ApplyBCs as LeanBSSN_ApplyBCs at CCTK_INITIAL after LeanBSSN_adm2bssn
{
} "Apply boundary conditions"
```

‌

In Lean, we extrapolate gammat at the end of the routine “LeanBSSN\_adm2bssn”, and sync as shown.

Our understanding was that “ApplyBCs” then applies the symmetry boundary conditions.

--
Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2648/empty-applybcs-call-in-leanbssnmol
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