[Users] BHNS simulation issues - Hamiltonian constraint violations and general problems

Samuel Tootle tootle at itp.uni-frankfurt.de
Sun Aug 22 01:59:17 CDT 2021

Hi Konrad,

The matter looks reasonable in all the iterations until the end, so that's good. Have you looked at the mesh grid to see if both objects are being tracked properly? You asked about this being a possibility in your first note, but didn't mention if you looked at the grid or not.


*From: *Konrad Topolski <k.topolski2 at student.uw.edu.pl>
*To: *Samuel Tootle <tootle at itp.uni-frankfurt.de>; Einstein Toolkit Users <users at einsteintoolkit.org>
*Date: *Aug 21, 2021 23:20:30
*Subject: *Re: [Users] BHNS simulation issues - Hamiltonian constraint violations and general problems

> Hi Sam
> I am sending the pictures of the density in a few iterations.
> Something indeed goes *very *bad (and possibly in the wrong direction pretty soon from the start).
> But before a chunk of the NS turns into atmosphere it doesn't look like it would end up like that.
> This is rho.maximum:
> 0 0 0.00181508688452629
> 16 0.4 0.00181562065714772
> 32 0.8 0.00181716349263237
> 48 1.2 0.00181971188439579
> 64 1.6 0.00182322915996771
> 80 2 0.00182773078378139
> And this is rho.average:
> 0 0 1.23447090415481e-07
> 16 0.4 1.2346439769246e-07
> 32 0.8 1.23490260581956e-07
> 48 1.2 1.23521771090518e-07
> 64 1.6 1.23554773904041e-07
> 80 2 1.23584518348538e-07
> sob., 21 sie 2021 o 23:03 Samuel Tootle <tootle at itp.uni-frankfurt.de> napisał(a):
>> Hi Konrad,
>> Have you checked the import of the ID from the hydro point of view (i.e. plot rho in for the first iterations). If you see drastic changes in the NS density in the initial iterations, it usually means the EOS manager isn't configured correctly which routinely results in the NS "vanishing" thereby destroying the solution and the evolution.
>> Cheers,
>> Samuel
>> *From: *Konrad Topolski <k.topolski2 at student.uw.edu.pl>
>> *To: *Einstein Toolkit Users <users at einsteintoolkit.org>
>> *Date: *Aug 21, 2021 22:30:57
>> *Subject: *[Users] BHNS simulation issues - Hamiltonian constraint violations and general problems
>>> Hi all
>>> I am trying to run a BH-NS simulation using at least one of some (and sometimes more) unofficial thors.
>>> That would be Kadath for the initial data and possibly THC for hydro evolution.
>>> I'm trying to run the simulation either with GRHydro or with THC.
>>> In both cases I believe that the initial data gets imported correctly - I have looked at some simple visuals which I'm attaching to this mail.
>>> However, as the simulation proceeds, huge hamiltonian constraint violations occur and e.x. the lapse gets driven to 0 globally. This can also be seen.
>>> How can I help this? Is it because the puncture is not tracked correctly? Trying to set up a PunctureTracker at the location of the black hole yields a failure very soon, as the shift at puncture is said to be (nan, nan, nan).
>>> I'm sending the .par files, outputs (.out), errors (.err) and visualization (.png).
>>> Best regards
>>> Konrad
>>> _______________________________________________
>>> Users mailing list
>>> Users at einsteintoolkit.org
>>> http://lists.einsteintoolkit.org/mailman/listinfo/users
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