[Users] Carpet moving grids

Erik Schnetter schnetter at cct.lsu.edu
Mon Jan 23 09:01:10 CST 2012


There are thorns that determine the location of the density maximum
and/or the centre of mass for neutron stars, and those thorns can feed
into Carpet's regridding method to have it track neutron stars. I have
not evolved moving neutron stars myself, so I can't tell you any more
details, but I hope others on this list will speak up.

Another method (that is probably not implemented yet) would be to
track the centre of the neutron stars in the same manner as the
puncture tracker, i.e. to derive an ODE that drives a pseudo-particle
along the density gradient. (In the puncture tracker, this
pseudo-particle moves along the shift vector instead.)


On Mon, Jan 16, 2012 at 6:03 PM, Petr Tsatsin <ptsatsin at fau.edu> wrote:
> Hello ,
> I'm trying to test a new version of my thorn which sets up initial data for
> moving neutron star. And I have couple questions about the Carpet moving
> grids. I was wondering if you could help answer it or suggest some recent
> documentation for Carpet which I can refer to? The question is simple: How
> to move grids in case of the moving neutron star? By looking at bbh
> parameter file I understood that Carpet gets information about position of
> the puncture from puncture tracker. Is there any trons which is providing
> this information in case of a neutron star or I have to write some thorn
> which is actually will track a center of the neutron star or its surface?
> Thank you!
> --
> Petr Tsatsin
> Graduate Student - Department of Physics
> Charles E. Schmidt College of Science
> Florida Atlantic University
> (561)-297-3386
> cell: 561-692-2040
> ptsatin at fau.edu, ptsatsin at gmail.com
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Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/

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