[yt-dev] Particle Deposition fields and grid boundaries

[Matthew Turk]

On Oct 7, 2014 10:41 PM, "Nathan Goldbaum" <nathan12343 at gmail.com> wrote:
>
>
>
> On Tue, Oct 7, 2014 at 7:45 PM, Matthew Turk <matthewturk at gmail.com>
wrote:
>>
>> On Tue, Oct 7, 2014 at 7:55 PM, Andrew Myers <atmyers2 at gmail.com> wrote:
>> > Hi Folks,
>> >
>> > I'm trying to understand how the particle deposition fields work for
>> > grid-based codes. Specifically, how does yt handle particles that are
close
>> > to the grid boundaries, so that the CIC interpolation stencil involves
cells
>> > on grid(s) other than the one that contains the particle position?.
Like,
>> > say I did:
>> >
>> > import yt
>> > ds = yt.load(fn)
>> > g = ds.index.grids[0]
>> > print g['deposit', 'all_cic']
>> >
>> > How does yt handle the fact that particles other than those living on
"g"
>> > can contribute to the total CIC density? Does it grab a layer of "ghost
>> > particles" somehow? I can't seem to find where that happens.
>> >
>> > Sorry if I'm just missing something obvious here...
>
>
> Andrew's original e-mail prompted me to make the following notebook,
which might prove useful for constructing a unit test:
>
> http://nbviewer.ipython.org/gist/ngoldbaum/eb40dfe74cd58a4e16ba
>
>>
>>
>> It doesn't, and you're not.  This is something it should do, but does
>> not currently.  If you're using a "smoothing" operation, it will, as
>> then it handles non-local particles, but deposit operations don't do
>> ghost zones.
>
>
> Smoothing is also only implemented for octrees.
>
>>
>>
>> This is something we should fix, and that we probably could by simply
>> making all the CIC fields ValidateSpatial(1).  Can you give that a
>> shot?
>
>
> Will this have interactions with https://trello.com/c/SFuSSoIo ?
>
> I think the answer is no, since we're querying particle fields and
selection doesn't require cascading interpolation, but I just want to
double-check.

It should be pretty fast.

>
>>
>> >
>> > Best,
>> > Andrew
>> >
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>> >
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