[petsc-users] DMSwarm

[Matthew Knepley]

On Wed, Mar 23, 2022 at 11:09 AM Joauma Marichal <
joauma.marichal at uclouvain.be> wrote:

> Hello,
>
> I sent an email last week about an issue I had with DMSwarm but did not
> get an answer yet. If there is any other information needed or anything I
> could try to solve it, I would be happy to do them...
>

I got a chance to run the code. I believe this undercovered a bug in our
implementation of point location with DMDA. I will make an Issue.

Your example runs correctly for me if you replace DM_BOUNDARY_GHOSTED with
DM_BOUNDARY_NONE in the DMDACreate3d.
Can you try that?

  Thanks,

     Matt


> Thanks a lot for your help.
>
> Best regards,
> Joauma
>
> ------------------------------
> *From:* Joauma Marichal
> *Sent:* Friday, March 18, 2022 4:02 PM
> *To:* petsc-users at mcs.anl.gov <petsc-users at mcs.anl.gov>
> *Subject:* DMSwarm
>
> Hello,
>
> I am writing to you as I am trying to implement a Lagrangian Particle
> Tracking method to my eulerian solver that relies on a 3D collocated DMDA.
>
> I have been using examples to develop a first basic code. The latter
> creates particles on rank 0 with random coordinates on the whole domain and
> then migrates them to the rank corresponding to these coordinates.
> Unfortunately, as I migrate I am loosing some particles. I came to
> understand that when I create a DMDA with 6 grid points in each 3
> directions and then set coordinates in between 0 and 1 using
> ,DMDASetUniformCoordinates and running on 2 processors, I obtain the
> following coordinates values on each proc:
> [Proc 0] X = 0.000000 0.200000 0.400000 0.600000 0.800000 1.000000
> [Proc 0] Y = 0.000000 0.200000 0.400000 0.600000 0.800000 1.000000
> [Proc 0] Z = 0.000000 0.200000 0.400000
> [Proc 1] X = 0.000000 0.200000 0.400000 0.600000 0.800000 1.000000
> [Proc 1] Y = 0.000000 0.200000 0.400000 0.600000 0.800000 1.000000
> [Proc 1] Z = 0.600000 0.800000 1.000000 .
> Furthermore, it appears that the particles that I am losing are (in the
> case of 2 processors) located in between z = 0.4 and z = 0.6. How can this
> be avoided?
> I attach my code to this email (I run it using mpirun -np 2 ./cobpor).
>
> Furthermore, my actual code relies on a collocated 3D DMDA, however the
> DMDASetUniformCoordinates seems to be working for staggered grids only...
> How would you advice to deal with particles in this case?
>
> Thanks a lot for your help.
>
> Best regards,
> Joauma
>
>
>
>

-- 
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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