Arcane offers two tools for converting or partitioning a mesh.

Mesh Partitioning Tool

The arcane_partition_mesh tool allows you to partition an existing mesh and generate a mesh file per partition. It is a parallel tool that uses ParMetis by default to perform the partitioning. This tool is installed in the bin directory of the Arcane installation.

Usage is as follows:

${ARCANE_INSTALL_ROOT}/bin/arcane_partition_mesh
  -n nb_proc
  -p nb_part
  --writer writer_service_name
  [--manifold-]
  [-Wp,arg1,arg2,...]
  mesh_file_name

Possible values for writer_service_name are services that implement IMeshWriter. For example:

MshMeshWriter (the default)
LimaMeshWriter
VtkLegacyMeshWriter: only for visualizing the result. The generated files cannot be used for code reading.

The input mesh file (mesh_file_name) can be in MSH format (extension .msh), VTK history format (extension .vtk), or a format supported by Lima (extension .mli2, .mli, .unf). When the input mesh is in MSH format, it is not possible to know beforehand if the mesh is non-manifold. By default, Arcane assumes it is a manifold mesh. If this is not the case, you must specify the --manifold- option in the command line.

The partitioner will run on nb_proc processes (via MPI) and will generate nb_part partitions. The number of partitions must be a multiple of the number of processes used. In the output, there will be one file per partition. The output files will be in the form CPU00000, CPU00001, ... with the extension corresponding to the mesh format (for example, .msh for the MSH format).

The -Wp option allows you to provide arguments for the parallel launcher (mpiexec or srun in general). For example, the value -Wp,-c,4 allows adding -c 4 to the parallel launcher.

Mesh Format MSH Handling

Warning: Reading and writing in MSH format has been experimental since version 3.16.0 of Arcane and currently has a number of limitations.

If the input and output format is MSH, each file will contain the same $Entities as the original format, as well as the periodicity information ($Periodics) for the partition concerned. The following limitations currently exist:

Only order 1 entities are managed
Periodicity information other than node pairs (master, slave) is consistent. Affine or entity information is not meaningful. For (master, slave) pairs, the pair will be present in the file if one of the two nodes is present in the partition.
Information about bounding boxes for $Entities is not managed
The original blocks of the MSH format are not necessarily saved, and the original $Entities numbers are not preserved.

Using Pre-cut Files

TODO

Usage Examples

The following example uses 2 processors to cut the onesphere.msh mesh into 4 partitions. The output file will be in VTK format.

./bin/arcane_partition_mesh -n 2 -p 4 --writer VtkLegacyMeshWriter onesphere.msh
ls
CPU00000.vtk
CPU00001.vtk
CPU00002.vtk
CPU00003.vtk

The following example uses 4 processors to cut the mesh_with_loose_items.msh mesh into 12 partitions. The output file will be in MSH format. Since the input mesh is non-manifold, the --manifold- option is used to specify this.

./bin/arcane_partition_mesh -n 4 -p 12 --writer MshMeshWriter --manifold- mesh_with_loose_items.msh
ls
CPU00000.msh
CPU00001.msh
...
CPU00010.msh
CPU00011.msh
CPU00012.msh

Mesh Conversion Tools

The arcane_convert_mesh tool allows you to convert a mesh file from one format to another.

Geometry Management