[Users] Some more Questions from a new User

[Erik Schnetter]

On Jan 15, 2014, at 9:05 , sruehe at astrophysik.uni-kiel.de wrote:

> Hello EinsteinToolkit-Community,
> 
> first of all i want thank you very much for the fast and helpful answer to
> my last Email.
> 
> I mentioned i'm at the beginning of my phd. So before i'm wasting too much
> time on working at something an other already knows, i want to ask some
> perhaps a little bit naively sounding questions.
> 
> I have studied smoothed particle hydrodynamics on a fixed spacetime, so i
> get the idea devolping a sph based thorn. I found no publications, so is
> perhaps anybody already working on this problem, or has one shown that
> this isn't possible?
> Because this is an community based development, it is quite interesting
> whether it could be an useful thorn.
> 
> I'm not sure whether my questions are answerable, but perhaps you can help
> me a second time.

Stefan

Some years ago I developed an SPH thorn for Newtonian hydrodynamics, and coupled this to a grid-based elliptic solver for self-gravity. This code was able to evolve e.g. single stars. This was a proof of concept; I did not push this into the direction new physics.

A GR SPH implementation would be easier since it does not need a Newtonian solver. Instead, one would need to define how to set a grid-base T_ab (for spacetime evolution, if desired), and to either evaluate or interpolate the metric at the particle locations. For both, Cactus offers supporting infrastructure.

The missing parts in Cactus have to do with handling particles. Cactus offers parallelized 1D arrays where particles can be stored. It does not yet offer methods to re-distribute particles between different processes. Of course, these can be added, and I would be very interesting in helping out.

Would you have time for a Google Hangout in the coming days to chat? I'm located in the EST time zone, six hours behind you, so your late afternoon would be a good time for me.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>
http://www.perimeterinstitute.ca/personal/eschnetter/

My email is as private as my paper mail. I therefore support encrypting
and signing email messages. Get my PGP key from http://pgp.mit.edu/.

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