[yt-users] Cell Volume in regions

[Desika Narayanan]

Hi Daniel,

Which changeset are you on?  (Matt can correct me on this) but I think
there was a time when the default was that over_refine_factor = 1.
 Though that wouldn't explain equal cell and particle numbers...

-d


On Wed, Jul 9, 2014 at 3:29 PM, Daniel <cunnama at gmail.com> wrote:

> I was comparing density and temperature to the cell_volume.
>
>
> On 9 July 2014 20:04, Nathan Goldbaum <nathan12343 at gmail.com> wrote:
>
>> Which fields were you comparing with?
>>
>>
>> On Wednesday, July 9, 2014, Daniel <cunnama at gmail.com> wrote:
>>
>>> 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
>>>> >>
>>>> >>
>>>> >> _______________________________________________
>>>> >> yt-users mailing list
>>>> >> yt-users at lists.spacepope.org
>>>> >> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>>> >>
>>>> >
>>>> >
>>>> > _______________________________________________
>>>> > yt-users mailing list
>>>> > yt-users at lists.spacepope.org
>>>> > http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>>> >
>>>> _______________________________________________
>>>> yt-users mailing list
>>>> yt-users at lists.spacepope.org
>>>> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>>>
>>>
>>>
>> _______________________________________________
>> yt-users mailing list
>> yt-users at lists.spacepope.org
>> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>>
>>
>
> _______________________________________________
> yt-users mailing list
> yt-users at lists.spacepope.org
> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.spacepope.org/pipermail/yt-users-spacepope.org/attachments/20140710/d6ddf761/attachment.html>