Dear Matt and Jed, Thank you so much for your insights.
Jed, as far as I know, the format is custom internal structure. I will double-check this. If it is used outside, I'm more than willing to contribute the reader. Best, Onur Sent with [Proton Mail](https://proton.me/) secure email. ------- Original Message ------- On Monday, October 30th, 2023 at 8:16 PM, Matthew Knepley <knep...@gmail.com> wrote: > On Mon, Oct 30, 2023 at 5:37 AM onur.notonur via petsc-users > <petsc-users@mcs.anl.gov> wrote: > >> 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. > > This is by far the easier approach. If you do not have meshes that are too > big to load in serial, I would do > this. Here is what you do: > > - Read in the mesh onto 1 process > - Mark the boundary conditions, probably with a DMLabel > - Make a Section over the mesh indicating what data you have for BC > - Create a Vec from this Section and fill it with boundary values > (DMCreateGlobalVector) > - Distribute the mesh, and keep the point SF (DMPlexDIstribute) > - Create a BC SF from the points SF (PetscSFCreateSectionSF) > - DIstribute the BC values using the BC SF (PetscSFBcast) > > Thanks, > > Matt > >> I would greatly appreciate your thoughts and any suggestions you might have >> regarding this approach. Looking forward to hearing your insights. >> >> Best regards, >> >> Onur > > -- > > 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/)
