[petsc-users] DMSWARM particle coordinates per rank

[Matthew Knepley]

On Fri, May 12, 2023 at 9:40 AM Matthew Young <
myoung.space.science at gmail.com> wrote:

> Got it.
>
> I'm specifically thinking about this in terms of the gather stage of my
> PIC code, where I loop over local particles to fill local density and flux
> arrays by linearly interpolating particle positions to the grid. The gather
> function currently assumes that the coordinates (i.e., the array
> representation of DMSwarmPICField_coor) of all particles on a given rank
> would correspond to only the global indices owned by that rank, via the
> relationship between indices and coordinates in the associated cell DM.
> Based on what you described, it sounds like I need to make sure that I
> initially lay down the particles so that their rank matches their
> coordinates.
>

Right now, yes. I will fix that before August.

  Thanks,

    Matt


> --Matt
> ==========================
> Matthew Young, PhD (he/him)
> Research Scientist II
> Space Science Center
> University of New Hampshire
> Matthew.Young at unh.edu
> ==========================
>
>
> On Fri, May 12, 2023 at 5:15 AM Matthew Knepley <knepley at gmail.com> wrote:
>
>> On Thu, May 11, 2023 at 9:15 PM Matthew Young <
>> myoung.space.science at gmail.com> wrote:
>>
>>> Does setting up a PIC-type DMSWARM with an associated cell DM guarantee
>>> that each MPI rank will own the particles with coordinates inside the
>>> bounds of the portion of the grid it owns?
>>>
>>
>> There is a caveat that we are currently fixing. Swarm communication is
>> setup to be nearest neighbor (since there is no coarse grid of
>> bounding boxes). So if your particles are initially in the right place, and
>> only move nearest neighbor, everything is fine. We are adding a hierarchy
>> of bounding boxes so that we can communicate anywhere.
>>
>>   Thanks,
>>
>>       Matt
>>
>>
>>> --Matt
>>> ==========================
>>> Matthew Young, PhD (he/him)
>>> Research Scientist II
>>> Space Science Center
>>> University of New Hampshire
>>> Matthew.Young at unh.edu
>>> ==========================
>>>
>>
>>
>> --
>> What most experimenters take for granted before they begin their
>> experiments is infinitely more interesting than any results to which their
>> experiments lead.
>> -- Norbert Wiener
>>
>> https://www.cse.buffalo.edu/~knepley/
>> <http://www.cse.buffalo.edu/~knepley/>
>>
>

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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