[yt-users] Cell Volume in regions

[Daniel]

Hi Matt,

No, just loading a standard GadgetDataset:

bbox = [[0.0, 1000000.0],
        [0.0, 1000000.0],
        [0.0, 1000000.0]]

unit_base = {'UnitLength_in_cm'         : 3.08568e+21,
             'UnitMass_in_g'            :   1.989e+43,
             'UnitVelocity_in_cm_per_s' :      100000}

pf = GadgetDataset("snapshot_050", unit_base = unit_base, bounding_box =
bbox)

Cheers,
Daniel


On 9 July 2014 17:58, Matthew Turk <matthewturk at gmail.com> wrote:

> Hi Daniel,
>
> On Wed, Jul 9, 2014 at 10:57 AM, Daniel <cunnama at gmail.com> wrote:
> > Hi Nathan,
> >
> > Thanks for getting back to me.
> >
> > That is odd, because then if my region includes all the particles I have
> > equal elements in cell_volume and all the other gas quantities?
> >
>
> Yup, that is a bit odd.  How are you loading the data?  Are you
> specifying either n_ref or over_refine_factor when doing so?
>
> -Matt
>
> > Kind Regards,
> > Daniel
> >
> >
> > On 9 July 2014 15:06, Nathan Goldbaum <nathan12343 at gmail.com> wrote:
> >>
> >> Hi Daniel,
> >>
> >> The cell_volume field is an alias for ('gas, 'cell_volume'), which for
> >> Gadget data corresponds to the volume of octree cells. In general there
> will
> >> be fewer octree cells than particles.  I'm a little surprised the
> numbers
> >> are so close since the default option is to refine octree cells when
> more
> >> than 64 particles are in a cell, although the precise structure of the
> >> octree will depend on the particle distribution.
> >>
> >> Nathan
> >>
> >>
> >> On Wednesday, July 9, 2014, Daniel <cunnama at gmail.com> wrote:
> >>>
> >>> Hi there,
> >>>
> >>> I am extracting a region from a Gadget dataset using the sphere
> function
> >>> and then attempting to access the "cell_volume" field.
> >>>
> >>> For some reason the number of elements in the cell volume field is not
> >>> equal to the number of particles in the region.
> >>>
> >>> For example I have 4341760 particles but only 4228930 cell volume
> >>> elements.
> >>>
> >>> I have extracted a sphere which encompassed all the particles and the
> >>> number of cell volume elements is then equal.
> >>>
> >>> Any ideas or advice would be greatly appreciated.
> >>>
> >>> Kind Regards,
> >>> Daniel
> >>
> >>
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> >>
> >
> >
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