[Users] question about ML_CCZ4 parameters

[Bruno Giacomazzo]

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 <schnetter at gmail.com>
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
> <bruno.giacomazzo at unimib.it> 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: bruno.giacomazzo at unimib.it
> > 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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>
>
>
> --
> Erik Schnetter <schnetter at gmail.com>
> http://www.perimeterinstitute.ca/personal/eschnetter/
>


-- 

Prof. Bruno Giacomazzo
Department of Physics
University of Milano-Bicocca
Piazza della Scienza 3
20126 Milano
Italy

email: bruno.giacomazzo at unimib.it
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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