Does DOLFINX_MPC have the support for Nedelec element

WjjSteve · January 28, 2025, 8:33am

Hello, I’m wondering that can I use DOLFINX_MPC to impose periodic BC for Nedelec elements? I find this Issue: Github repo, but don’t find any update in it. So I guess that this is not possible so far, is that true?

Thanks in advance.

sbhasan · January 28, 2025, 5:34pm

It is possible with some kinks. Please refer to the following:

I was able to use the method for 2D geometries and did not encounter the anomaly indicated in the thread. But that somehow meant I did not stumble upon the corner case?

Also look down for an alternate approach by @dokken that makes the mesh itself periodic.

dokken · January 29, 2025, 12:28pm

The implementation with the periodic mesh referenced in the above post has been extended to parallel in:

gist.github.com

https://gist.github.com/jorgensd/e0e610fd17f73337178bc12788fa17ba#file-script-py

README.md

# TODO

1.  Create interface that reads in the original global index from MSH directly
```python
from mpi4py import MPI
import dolfinx.io
import numpy.typing as npt
import gmsh

gmsh.initialize()

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create_mesh.py

import gmsh
import numpy as np
import argparse
from pathlib import Path

parser = argparse.ArgumentParser(description="Create a mesh for a box in a channel")
parser.add_argument(
    "--res", type=float, default=0.05, help="Resolution of the mesh (at inlet)"
)
parser.add_argument(

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mwe_failing.py

from dolfinx import fem
from dolfinx.fem.petsc import LinearProblem
from dolfinx.io.gmshio import model_to_mesh
from dolfinx.io import VTXWriter
import ufl
import gmsh
import dolfinx
from petsc4py import PETSc
from basix.ufl import element
from mpi4py import MPI

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There are more than three files. show original

It will likely be incorporated in scifem in the foreseeable future.

filliong · February 4, 2025, 7:32pm

Dear Dokken,

I am not very experienced with Fenicsx, but I am also interested to use it to solve an EM problem with periodic boundary conditions using Nedelec elements. I am interested by both 2D and 3D problems on simple conforming meshes. In 3D, I would have to impose 2 different periodic boundary conditions, in x and y (for example). Is it possible to do this with your function create_periodic_mesh (by calling it twice).

Also, I was wondering if it would be simpler to generate a periodic mesh directly with GMSH (or any other meshing tools). What would be the behavior of Fenicsx when loading such a mesh? Would it work directly with MPI? Or do we need some mappings somewhere, or some other features?

dokken · February 4, 2025, 7:59pm

Currently no, but you can call it with a single map, as for instance done in:

gist.github.com

https://gist.github.com/jorgensd/e0e610fd17f73337178bc12788fa17ba#file-mwe_failing-py-L178

README.md

# TODO

1.  Create interface that reads in the original global index from MSH directly
```python
from mpi4py import MPI
import dolfinx.io
import numpy.typing as npt
import gmsh

gmsh.initialize()

This file has been truncated. show original

create_mesh.py

import gmsh
import numpy as np
import argparse
from pathlib import Path

parser = argparse.ArgumentParser(description="Create a mesh for a box in a channel")
parser.add_argument(
    "--res", type=float, default=0.05, help="Resolution of the mesh (at inlet)"
)
parser.add_argument(

This file has been truncated. show original

mwe_failing.py

from dolfinx import fem
from dolfinx.fem.petsc import LinearProblem
from dolfinx.io.gmshio import model_to_mesh
from dolfinx.io import VTXWriter
import ufl
import gmsh
import dolfinx
from petsc4py import PETSc
from basix.ufl import element
from mpi4py import MPI

This file has been truncated. show original

There are more than three files. show original

which was made together with Cristian Ciraci.

In theory, one could simplify the code I have made by using information from GMSH. I’ve not had time to do this yet. In the aforementioned example you see gmsh being used for the periodic map on a cube.

The function from script.py should work with MPI out of the box.

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Does DOLFINX_MPC have the support for Nedelec element

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