[petsc-users] Writing VTK output

[Jed Brown]

You're using pretty old versions of all software; I'd recommend upgrading. I recommend choosing the file name "solution.vtu" to use the modern (non-legacy) format. Does that work for you?

Sami BEN ELHAJ SALAH <sami.ben-elhaj-salah at ensma.fr> writes:

> Dear Petsc Developer team,
>
> I solved a linear elastic problem in 3D using a DMPLEX. My system is converging, then I would like to write out my solution vector to a vtk file where I use unstructured mesh. Currently, I tried two algorithms and I have the same result.
>
> 1) Algorithm 1    
> err = SNESSolve(_snes, bc_vec_test, solution);
> CHKERRABORT(FOX::Parallel::COMM_WORLD,err);
> PetscViewer vtk; 
> PetscViewerVTKOpen(FOX::Parallel::COMM_WORLD,"solution.vtk",FILE_MODE_WRITE,&vtk); 
> VecView(solution,vtk);
> PetscViewerDestroy(&vtk);
>
>
> 2) Algorithm 2
> err = SNESSolve(_snes, bc_vec_test, solution);
> CHKERRABORT(FOX::Parallel::COMM_WORLD,err);
> PetscViewer vtk; 
> PetscViewerCreate(FOX::Parallel::COMM_WORLD, &vtk); 
> PetscViewerSetType(vtk, PETSCVIEWERVTK); 
> PetscViewerFileSetName(vtk, "sol.vtk"); 
> VecView(solution, vtk); 
> PetscViewerDestroy(&vtk);
>  
> The result seems correct except for the rotation order of the nodes (see the red lines on gmsh and vtk file respectively). Then, I visualized my vtk file with paraview, and I remarked that my geometry is not correct and not conserved when comparing it with my gmsh file. So, I didn’t understand why the rotation order of nodes  is not conserved when saving my result to a vtk file?
>  
> Other information used:
> - gmsh format 2.2 
> - Vtk version: 7.1.1
> - Petsc version: 3.13/opt 
>
> Below my two files gmsh and vtk:
>
> Gmsh file:
> $MeshFormat
> 2.2 0 8
> $EndMeshFormat
> $Nodes
> 12
> 1 0.0 10.0 10.0
> 2 0.0 0.0 10.0
> 3 0.0 0.0 0.0
> 4 0.0 10.0 0.0
> 5 10.0 10.0 10.0
> 6 10.0 0.0 10.0
> 7 10.0 0.0 0.0
> 8 10.0 10.0 0.0
> 9 20.0 10.0 10.0
> 10 20.0 0.0 10.0
> 11 20.0 0.0 0.0
> 12 20.0 10.0 0.0
> $EndNodes
> $Elements
> 2
> 1 5 2 68 60 1 2 3 4 5 6 7 8
> 2 5 2 68 60 5 6 7 8 9 10 11 12
> $EndElements
>
> Vtk file :
> # vtk DataFile Version 2.0
> Simplicial Mesh Example
> ASCII
> DATASET UNSTRUCTURED_GRID
> POINTS 12 double
> 0.000000e+00 1.000000e+01 1.000000e+01
> 0.000000e+00 0.000000e+00 1.000000e+01
> 0.000000e+00 0.000000e+00 0.000000e+00
> 0.000000e+00 1.000000e+01 0.000000e+00
> 1.000000e+01 1.000000e+01 1.000000e+01
> 1.000000e+01 0.000000e+00 1.000000e+01
> 1.000000e+01 0.000000e+00 0.000000e+00
> 1.000000e+01 1.000000e+01 0.000000e+00
> 2.000000e+01 1.000000e+01 1.000000e+01
> 2.000000e+01 0.000000e+00 1.000000e+01
> 2.000000e+01 0.000000e+00 0.000000e+00
> 2.000000e+01 1.000000e+01 0.000000e+00
> CELLS 2 18
> 8  0 3 2 1 4 5 6 7
> 8  4 7 6 5 8 9 10 11
> CELL_TYPES 2
> 12
> 12
> POINT_DATA 12
> VECTORS dU_x double
> 2.754808e-10 -8.653846e-11 -8.653846e-11
> 2.754808e-10 8.653846e-11 -8.653846e-11
> 2.754808e-10 8.653846e-11 8.653846e-11
> 2.754808e-10 -8.653846e-11 8.653846e-11
> 4.678571e-01 -9.107143e-02 -9.107143e-02
> 4.678571e-01 9.107143e-02 -9.107143e-02
> 4.678571e-01 9.107143e-02 9.107143e-02
> 4.678571e-01 -9.107143e-02 9.107143e-02
> 1.000000e+00 -7.500000e-02 -7.500000e-02
> 1.000000e+00 7.500000e-02 -7.500000e-02
> 1.000000e+00 7.500000e-02 7.500000e-02
> 1.000000e+00 -7.500000e-02 7.500000e-02
>
> Thank you in advance and have a good day !
>
> Sami,
>
> --
> Dr. Sami BEN ELHAJ SALAH
> Ingénieur de Recherche (CNRS)
> Institut Pprime - ISAE - ENSMA
> Mobile: 06.62.51.26.74
> Email: sami.ben-elhaj-salah at ensma.fr
> www.samibenelhajsalah.com <https://samiben91.github.io/samibenelhajsalah/index.html>