scripts

Examples of CoMMA python module

Dependencies

In most of the scripts here, we use the string format {var=}, hence python3.8 or later is needed.

Two main libraries are used, both are available on GitHub under the MIT license:

• meshio for reading and exporting meshes in various formats
• dualGPy for building the dual graph of a mesh

Description

All the examples in the directory have, roughly speaking, the same structure:

1. Create / Read a mesh
2. Prepare the mesh with dualGPy
3. Agglomerate with CoMMA
4. Export the results to .vtu thanks to meshio

A brief description of the scripts in this directory:

• ex_default_dualGPy.py: Build a Cartesian 2D mesh with dualGPy default constructor. Simple switches enable the user to choose anisotropy, dimension and other parameters for CoMMA. Useful for familiarizing with:
  • Prepare a mesh with dualGPy so that it can be handled by CoMMA
  • Arguments and outputs of CoMMA call
  • Preparing the output (subdivision in classes) for meshio
• ex_read_mesh.py: Read an existing mesh via meshio and agglomerate it. Simple switches enable the user to choose anisotropy, dimension and other parameters for CoMMA. Useful for familiarizing with:
  • Reading a mesh with meshio and preparing it with dualGPy
  • Preparing the output (subdivision in classes and/or in cell types) for meshio
• ex_aniso_lines.py: Show how to draw anisotropic lines obtained from CoMMA. Useful for familiarizing with:
  • CoMMA's definition of anisotropic lines
  • Drawing anisotropic lines with dualGPy
• ex_several_agglo_levels.py: Show how to agglomerate several times the same mesh using CoMMA. Useful for familiarizing with:
  • Running several agglomeration steps on the same mesh, each time preparing the result of the previous step for the following one
  • Outputting more than one field via meshio
• ex_rae.py: Agglomeration of a 2D RAE2822 mesh. We use here different features:
  • Perfectly selection of the BL by looking at the cell-type (only squares)
  • Computation of the (reciprocal) of the wall-distance to be used as weights to give higher priority to cells near the wall
  • Several agglomeration levels
  • Modification of the anisotropic lines after the first level

Deprecated

Some old deprecated examples:

• test_from_comma_source.py: Build a hand-picked 2D mesh, agglomerate it with CoMMA and export the result
• test_dualGPy.py: Build a hand-picked 2D mesh of quads and triangles with dualGPy, agglomerate it with CoMMA and export the result
• test_square.py: Build a Cartesian 2D mesh with dualGPy default constructor, agglomerate it with CoMMA and export the result

Formatting

The python files are formatted with Black and isort. A configuration file is available, see pyproject.toml.