Chair: Peter Minutes: Leo
Present: David, Leo, Miguel, Peter, Roland, Yosef, Zach
* Any SpEC updates? No, Roland will send an email.
* Any updates on the status of LORENE? Not from anyone in the call. Roland will email Josh about this.
* Summer school updates? The program is ready. You can find it on the ETK summer school site (https://einsteintoolkit.github.io/et2021uiuc/). All invited speakers have been contacted. There is still a hole in the schedule which the organizers are currently trying to fill.
* David: is there any plans on having a hardware expert for the ETK? No, there are those who are able to help, but not someone dedicated to only doing that.
* David: what exactly is the configuration script doing? Difficult to answer, because the entire process is scripted and involves a decision tree. But in a nutshell, a few Perl scripts are called and then make is invoked.
* Next ET release: need to find a new release manager.
* Unanswered questions in the mailing list: ** http://lists.einsteintoolkit.org/pipermail/users/2021-July/008056.html Roland: Likely the answer to the question is simply that there are reflections happening at the refinement boundaries. Particularly the fact that the constraint violations appear to increase towards the corner of the AMR grids is a good indicator that this is being caused by spurious reflections and interpolation errors. It is possible to mitigate these effects by tweaking some of the parameters. Zach: Very hard to answer and reproduce without having the user's parameter file. It could be an issue with the con2prim in the hydro code, in which e.g. a fluid velocity is coupled to one of the CCZ4 modes and leads to these large errors. Also, why use CCZ4 here? Has BSSN already been tested?
** http://lists.einsteintoolkit.org/pipermail/users/2021-July/008060.html Roland: The fact that PPM and WENO display different behavior in the maximum density over time is not too surprising since the two are quite different. However, the fact that WENO and WENO-Z also display large differences is a bit strange, as the latter is just a slight modification of the former with a few extra things added. Zach: I don't really know what to make of the plots. It may be a problem with the WENO implementation in GRHydro. Would reply to the user: could you please simplify the test a bit? Looking at a BNS is too difficult a test to diagnose these issue, so it would be better to look at convergence tests for a single NS. Roland: Also suspects that the user is using the MHD option in GRHydro but with zero magnetic fields. Zach: Again, it would be easier for us to understand what the user is doing if we had access to their parameter file. Another test that could be performed would be to start with a single NS and then place a refinement level *inside* the star. All the refinement boundary issues should be greatly amplified, but the system should still be stable.
Next week's chair: Roland Next week's minutes: Bill