Re: Compute Local density for No Gas particles

From: Yves Revaz <>
Date: Mon, 15 Oct 2012 08:59:22 +0200

Dear Magda,

This is not trivial to do in Gagdget2, as to compute the density
(and hydro) you need to use the SphP structure. But this structure
exists by default only for type 0 (gas) particles.

If you don't use the hydro part, one very easy way to implement what
you need is to move your type 2 particles into time 0, and disable the
hydro forces.

If this is not sufficient for your purpose, you need to extend the SphP
structure to
other particles. This is of course possible, but much more tricky.


On 10/15/2012 08:42 AM, Magda Guglielmo wrote:
> Dear gadget list,
> I need Gadget2 to compute the local density and the number of
> neighbours in the current smoothing radius for particles of type 2
> (disk particles). My understanding is that Gadget normally does only
> for gas particles (SPH), so I need to modify the density.c routine.
> I am not running any SPH Hydro simulation, so I don't use this
> routine, but I would like to keep the Gadget structure unchanged so
> that it will keep working.
> I saw that a similar topic has been posted the web archive, but I did
> not find any answer or suggestions.
> Does anyone has any suggestion on how I can do this in the simplest
> way possible?
> Thank you in advance
> Best Regards

                                                 (o o)
   Dr. Yves Revaz
   Laboratory of Astrophysics
   Ecole Polytechnique Fédérale de Lausanne (EPFL)
   Observatoire de Sauverny     Tel : ++ 41 22 379 24 28
   51. Ch. des Maillettes       Fax : ++ 41 22 379 22 05
   1290 Sauverny             e-mail :
   SWITZERLAND                  Web :
Received on 2012-10-15 08:59:23

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