I like the CGNS workflow for this, at least with quadratic and cubic elements. You can use options like -snes_view_solution cgns:solution.cgns (configure with --download-cgns). It can also monitor transient solves with flexible batch sizes (geometry and connectivity are stored only once within a batch of output frames).
Anna Dalklint via petsc-users <petsc-users@mcs.anl.gov> writes: > Hello, > > We have created a finite element code in PETSc for unstructured meshes using > DMPlex. The first order meshes are created in gmsh and loaded into PETSc. To > introduce higher order elements, e.g. 10 node tetrahedral elements, we start > from scratch using PetscSection and loop over the relevant points it the DM > to introduce additional degrees-of-freedom (example; for 10 node tets we have > 4 vertices “nodes” and 6 edge “nodes”). The coordinates of the new “nodes” > are obtained by interpolation using the finite element basis functions. > > The simulations seem to run well, but we face issues when trying to visualize > the results in ParaView. We have tried to use both CGNS and HDF5+XDMF file > formats for e.g. VecView. CGNS works, but the edge degrees-of-freedom appear > to not be interpolated correctly (we observe oscillations in the fields, > don’t know if this is a PETSc och ParaView issue). Also, we would prefer to > use another file format than CGNS since it does not appear to directly allow > timeseries (at least ParaView doesn’t recognize it). We haven’t got the > HDF5+XDMF file format to work at all when running on more than one core (the > mesh is highly distorted when saving using VecView and DMView + running the > “petsc_gen_xdmf.py” script on the .h5 output file). > > VTU format works but then only the vertices’ degrees-of-freedom are > visualized. As far as we have understood it, this is because VTU/VTK only > supports degrees-of-freedom on vertices/cell level. > > Does anyone have any idea of how to visualize fields generated from higher > order elements in ParaView? Or understand what we might be doing wrong? > > Best regards, > Anna
