Mesh Manipulation Tools

Introduction

There are several simple meshing operations that can be done easily enough from the command line. For example, creating a 3D cartesian block of a given size with a specified uniform cell size only requires 4 parameters. We have developed a suite of functions called cgnsUtilities that can be called from the command line to perform simple, repeatable tasks like this.

Files

Navigate to the directory aero/meshing/volume in your tutorial folder. We will perform operations on the file wing_vol.cgns.

cgnsUtilities Operations

To get a list of all of the operations available with cgnsUtilities, run the command

cgns_utils -h

For any cgns_utils operation, you can add the argument -h to get information about the required and optional parameters (e.g. cgns_utils symmzero -h).

Coarsening a volume mesh

The command cgns_utils coarsen takes a volume mesh and coarsens it by removing every other node in all three dimensions. Although our volume mesh is already very coarse, we can coarsen it even further. This function is more useful in instances where we start with a very fine mesh. To coarsen the mesh run the following from the terminal:

cgns_utils coarsen wing_vol.cgns wing_vol_coarsened.cgns

The original and the coarsened meshes are shown below.

CGNS Viewer

Bundled with cgnsUtilities is a very barebones mesh viewing software that can be useful for debugging problems with the mesh such as incorrect boundary conditions or missing face-to-face connections. CGNS Viewer can be run from the terminal with the command

cgnsview

More details to come later.