Barry, thanks for the information! Cheers, Bruno
Il giorno gio 9 giu 2022 alle ore 00:52 Barry Wardell < [email protected]> ha scritto: > Hi all, > > The CCZ4 code was written initially by Dana Alic. Erik (and others) > subsequently made improvements since then. As far as I know, it should be > effectively implementing the equations as in gr-qc:1106.2254. > > With regards to the k3 parameter, Dana previously had this to say: > "[GammaShift] should actually be 'real' and its default value set to 0.5, > as it corresponds to the k3 parameter in the CCZ4 paper ( > http://arxiv.org/pdf/1106.2254.pdf). This is important, because it leads > to fast instabilities if it is set to 1 and coupled with non-zero values of > the damping terms." > > I hope this helps, > Barry > > On Thu, 2 Jun 2022 at 16:02, Michael Muller <[email protected]> wrote: > >> Hi Bruno, >> >> I have gone through the notebook in the past and from what I could see, >> the version of paper I (10.1103/PhysRevD.85.064040) >> is implemented in the code, kappa_3 is encoded in the parameter ' >> ML_CCZ4::GammaShift', and the changes for the >> scaling of kappa_1 and kappa_2 with the lapse (eq. 27 and 28 in paper >> II, 2013) are not implemented. >> >> I hope this helps. >> Best, >> Michael Müller >> ------------------------------ >> *From:* [email protected] < >> [email protected]> on behalf of Bruno Giacomazzo < >> [email protected]> >> *Sent:* Thursday, June 2, 2022 10:04 AM >> *To:* Erik Schnetter <[email protected]> >> *Cc:* Einstein Toolkit Users <[email protected]>; Paolo >> Garimberti <[email protected]> >> *Subject:* Re: [Users] question about ML_CCZ4 parameters >> >> >> CAUTION: This email originated from outside of the University of Guelph. >> Do not click links or open attachments unless you recognize the sender and >> know the content is safe. If in doubt, forward suspicious emails to >> [email protected] >> >> Hi Erik, >> thanks a lot for the offer to help. I will try to have a look by >> myself first at the mathematica notebook. >> >> Unless anybody else knows on what paper CCZ4 in McLachlan is based on. :-) >> >> Cheers, >> Bruno >> >> >> Il giorno mer 1 giu 2022 alle ore 22:48 Erik Schnetter < >> [email protected]> ha scritto: >> >> 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/ >> >> >> >> -- >> >> 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 >> > -- 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 ----------------------------------------------------------------------
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