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From: Ali Snedden <Ali.P.Snedden.3_at_nd.edu>

Date: Thu, 11 Sep 2014 16:40:31 -0400

Actually, I think my question is answered here.

http://www.mpa-garching.mpg.de/gadget/gadget-list/0136.html

~Ali

On Thu, Sep 11, 2014 at 1:51 PM, Ali Snedden <Ali.P.Snedden.3_at_nd.edu> wrote:

*> Hello,
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*>
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*> I am trying to work through the units used in SphP[*].Entropy and
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*> SphP[*].Pressure. I worked through the units of Entropy (see the
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*> initialization of Entropy in read_ic.c and init.c) and I get units of :
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*>
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*> (Internal Energy * (Internal Length)^2 / (Internal Mass^(5/3)) ) in
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*> Euclidian (i.e. NOT comoving) coordinates.
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*>
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*> However when computing the Pressure, in density.c
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*>
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*> SphP[i].Pressure = (SphP[i].Entropy + SphP[i].DtEntropy * dt_entr) *
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*> pow(SphP[i].Density, GAMMA).
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*>
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*> This is confusing to me, because it appears that Density is in comoving
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*> coordinates and Entropy is in Euclidian coordinates. I would expect that
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*> they should be in the same coordinate system. I would think that there is
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*> a couple of factors of the scale factor (i.e. All.Time) missing. This
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*> would convert the Entropy into comoving coordinates so that the Pressure is
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*> in comoving coordinates.
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*>
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*> If Density really is in comoving coordinates and Entropy is in Euclidian
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*> coordinates, then is the Pressure in comoving or Euclidian coordinates?
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*>
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*>
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*> Sincerely,
*

*> Ali
*

*>
*

Received on 2014-09-11 22:40:37

Date: Thu, 11 Sep 2014 16:40:31 -0400

Actually, I think my question is answered here.

http://www.mpa-garching.mpg.de/gadget/gadget-list/0136.html

~Ali

On Thu, Sep 11, 2014 at 1:51 PM, Ali Snedden <Ali.P.Snedden.3_at_nd.edu> wrote:

Received on 2014-09-11 22:40:37

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