Thanks a lot, Stefano. I tried DMPlexGetGatherDM and DMPlexDistributeField. It can give what we expected. The final gatherDM is listed as follows, rank 0 has all information (which is right) while rank 1 has nothing. Then I tried to feed this gatherDM into adaptMMG on rank 0 only (it seems MMG works better than ParMMG, that is why I want MMG to be tried first). But it was stuck at collective petsc functions in DMAdaptMetric_Mmg_Plex(). By the way, the present work can work well with 1 rank.
Do you have any suggestions ? Build a real serial DM? Thanks a lot. Xiaodong DM Object: Parallel Mesh 2 MPI processes type: plex Parallel Mesh in 3 dimensions: Number of 0-cells per rank: 56 0 Number of 1-cells per rank: 289 0 Number of 2-cells per rank: 452 0 Number of 3-cells per rank: 216 0 Labels: depth: 4 strata with value/size (0 (56), 1 (289), 2 (452), 3 (216)) celltype: 4 strata with value/size (0 (56), 1 (289), 3 (452), 6 (216)) Cell Sets: 2 strata with value/size (29 (152), 30 (64)) Face Sets: 3 strata with value/size (27 (8), 28 (40), 101 (20)) Edge Sets: 1 strata with value/size (10 (10)) Vertex Sets: 5 strata with value/size (27 (2), 28 (6), 29 (2), 101 (4), 106 (4)) Field Field_0: adjacency FEM On Fri, Apr 18, 2025 at 10:09 AM Stefano Zampini <stefano.zamp...@gmail.com> wrote: > If you have a vector distributed on the original mesh, then you can use > the SF returned by DMPlexGetGatherDM and use that in a call to > DMPlexDistributeField > > Il giorno ven 18 apr 2025 alle ore 17:02 neil liu <liufi...@gmail.com> ha > scritto: > >> Dear PETSc developers and users, >> >> I am currently exploring the integration of MMG3D with PETSc. Since MMG3D >> supports only serial execution, I am planning to combine parallel and >> serial computing in my workflow. Specifically, after solving the linear >> systems in parallel using PETSc: >> >> 1. >> >> I intend to use DMPlexGetGatherDM to collect the entire mesh on the >> root process for input to MMG3D. >> 2. >> >> Additionally, I plan to gather the error field onto the root process >> using VecScatter. >> >> However, I am concerned that the nth value in the gathered error vector >> (step 2) may not correspond to the nth element in the gathered mesh (step >> 1). Is this a valid concern? >> >> Do you have any suggestions or recommended practices for ensuring correct >> correspondence between the solution fields and the mesh when switching from >> parallel to serial mode? >> >> Thanks, >> >> Xiaodong >> > > > -- > Stefano >
