[petsc-users] Advices on creating DMPlex from custom input format

[onur.notonur]

Hi,

I hope this message finds you all in good health and high spirits.

I wanted to discuss an approach problem input file reading/processing in a solver which is using PETSc DMPlex. In our team we have a range of solvers, they are not built on PETSc except this one, but they all share a common problem input format. This format includes essential data such as node coordinates, element connectivity, boundary conditions based on elements, and specific metadata related to the problem. I create an array for boundary points on each rank and utilize them in our computations, I am doing it hardcoded currently but I need to start reading those input files, But I am not sure about the approach.

Here's what I have in mind:

- - Begin by reading the node coordinates and connectivity on a single core.
- Utilize the DMPlexCreateFromCellListPetsc() function to construct the DMPlex.
- Distribute the mesh across processors.
- Proceed to read and process the boundary conditions on each processor. If the global index of the boundary element corresponds to that processor, we process it; otherwise, we pass.

Additionally, maybe I need to reorder the mesh. In that case I think I can use the point permutation IS obtained from the DMPlexGetOrdering() function while processing boundary conditions.

Also I have another approach in my mind but I don't know if it's possible: Read/construct DMPlex on single core including boundary conditions. Store BC related data in Vec or another appropriate data structure. Then distribute this BC holding data structure too as well as DMPlex.

I would greatly appreciate your thoughts and any suggestions you might have regarding this approach. Looking forward to hearing your insights.

Best regards,

Onur
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