Bruno Although I was probably around when the CCZ4 formulation was implemented, I don't recall.
I usually resolve to archaeology, comparing the equations in the respective Mathematica scripts to equations found in publications. If no one else speaks up, I can assist with this – we'd set up a Zoom meeting, and I can show how to read (or modify!) the Mathematica script that implements these equations. -erik On Tue, May 31, 2022 at 6:21 AM Bruno Giacomazzo <[email protected]> wrote: > > Together with a student of mine we are trying to use the CCZ4 formulation > implemented in McLachlan. We saw that most parameters are the same as in > BSSN, but there are damping factors that need to be selected. > > In Alic et al 2013 (https://link.aps.org/doi/10.1103/PhysRevD.88.064049) they > mention 3 damping factors (k1, k2, and k3), but in the param.ccl of > McLachlan/ML_CCZ4 only k1 and k2 are mentioned (assuming they are the same). > > Is it because k3 is hardcoded to the value suggested in Alic et al 2013? Or > does McLachlan/ML_CCZ4 use a different set of evolution equations (in which > case, is there a reference)? > > We were able to find some example parameter files (for example the ones from > the Parma group https://einstein.pr.infn.it/gravity/Research/BNS2015.html) > and we found that they used indeed k1 and k2 from Alic et al 2013: > ML_CCZ4::dampk1 = 0.05 > ML_CCZ4::dampk2 = 0 > > We also saw that they added ML_CCZ4::ML_Theta to the Dissipation vars and set > ML_CCZ4::apply_dissipation = "never". > The other parameters look the same as when using BSSN. > > Since I never used ML_CCZ4 I want to be sure that I'm setting the parameters > correctly and the damping factors seem to be the most delicate point. > > Thanks, > Bruno > > -- > > Prof. Bruno Giacomazzo > Department of Physics > University of Milano-Bicocca > Piazza della Scienza 3 > 20126 Milano > Italy > > email: [email protected] > phone: (+39) 02 6448 2321 > web: http://www.brunogiacomazzo.org > > ---------------------------------------------------------------------- > There are only 10 types of people in the world: > Those who understand binary, and those who don't > ---------------------------------------------------------------------- > > _______________________________________________ > Users mailing list > [email protected] > http://lists.einsteintoolkit.org/mailman/listinfo/users -- Erik Schnetter <[email protected]> http://www.perimeterinstitute.ca/personal/eschnetter/ _______________________________________________ Users mailing list [email protected] http://lists.einsteintoolkit.org/mailman/listinfo/users
