Re: Compute Local density for No Gas particles

From: Magda Guglielmo <magda.guglielmo_at_gmail.com>
Date: Thu, 22 Nov 2012 11:29:06 +1100

Hi Arman,

thank you very much for the code.
I am trying it, but I have some question about.
In the function in InSubBox the code will call inbox using header.BoxSize
and All.Rc, the question is where does the code assign value to All.Rc?
Thank you in advance for your help.
Regards
Magda


On Mon, Oct 15, 2012 at 10:00 PM, Arman Khalatyan <arm2arm_at_gmail.com> wrote:

> Hi Magda, there is no simple way to calculate density with Gadget2, but
> you can make it work with a few changes.
>
> please check the attachment . I have my modified version of read_io.c
> In Makefile you need to define which particles to move to SPH slot:
> for example add this lines to calculate density of DM particles.
> OPT +=-DDM_ONLY # calculate density only for DM or STARS
> OPT += -DALL_RHO
>
> In main.c:
> comment out run(); routine then:
>
> ngb_treebuild();
> savepositions(1);
>
> Probably you need to change io.c to save results into some another block
> instead of RHO, let say:
> #ifdef DM_ONLY
> strcpy(RHONAME, "RHO1");
> strcpy(HSMLNAME,"H1 ");
> #endif
>
>
> Then in function fill_Tab_IO_Labels() in switch statement:
> case IO_RHO:
> strncpy(Tab_IO_Labels[IO_RHO], RHONAME, 4);
> break;
> case IO_HSML:
> strncpy(Tab_IO_Labels[IO_HSML]
> , HSMLNAME, 4);
> break;
>
>
> Thats it.
>
> Arman.
>
>
> On Mon, Oct 15, 2012 at 8:59 AM, Yves Revaz <yves.revaz_at_epfl.ch> wrote:
>
>> **
>> 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.
>>
>> yves
>>
>>
>>
>> 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)
>> --------------------------------------------oOO--(_)--OOo-------
>> 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 : Yves.Revaz_at_epfl.ch
>> SWITZERLAND Web : http://www.lunix.ch/revaz/
>> ----------------------------------------------------------------
>>
>>
>>
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>
>
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Received on 2012-11-22 01:29:08

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