Importing Volume Meshes

CCM Format

The CCM file type is native to the STAR-CD solver (STAR) and pre-processor (pro-STAR).

Since STAR-CD v4.04, the following extensions are used:

• .ccmg signifies a CCM file from pro-STAR containing geometry data.
• .ccmp signifies a CCM file from STAR (the solver) containing solution post-processing data.
• .ccmt signifies a CCM file from STAR containing transient post-processing data.

Simcenter STAR-CCM+ can read the .ccmg file directly to retrieve the mesh. When reading a .ccmp, the corresponding .ccmg is also read in at the same time so that the post data can be displayed. Only the data corresponding to the first state in the .ccmp file is available. In the case of transient .ccmt files, rename them as .ccmp files, which allows the first time step saved on the file to be read in. Other time step values in the same file are available.

Mesh data is exported to the file by pro-STAR using the command GEOM. In the case of the .ccmp and/or .ccmt files, solution data is saved by the STAR solver directly (as part of an analysis run). pro-STAR can also write solution mapped data (command SMAP) to the .ccmp file as part of a restart.

A scale factor for the mesh is saved to the file during export from pro-STAR but the vertices that are contained in the file are not scaled. The scale factor is used to redimension the mesh during the import process into Simcenter STAR-CCM+.

Each collection of cells in pro-STAR with the same properties (material label, material index, porosity index, spin index and group index) is considered to be one region. Different cell types do not result in different region definitions unless one of the above properties differs for the cell type.

The CCM file format is the recommended way of transferring meshes and post data from STAR-CD to Simcenter STAR-CCM+. Simcenter STAR-CCM+ can also export both mesh and solution data to STAR-CD using the CCM file format, although not all solution variables are transferable.

NGEOM Format

The .ngeom file type was originally designed for use with the COMET solver, but is now replaced by the CCM format.

The .ngeom format is exported by pro-STAR using the NGEOM command and can only contain mesh data. If the appropriate scale factor was applied during the export process, the vertices that are contained in the file conform to SI and no further action is required on importing the file into Simcenter STAR-CCM+. The scale factor that is used is also saved to the file but is not used. Boundary types are inferred from boundary names, and if no inference can be made, then a boundary is assigned the type wall.

Each collection of cells with the same properties (material label, material index, porosity index, spin index and group index) in pro-STAR is considered to be one region. Cell types do not affect the region definition unless one of the above properties differs.

Gridgen Meshes

Gridgen can export Fluent format files with the.cas extension and Simcenter STAR-CCM+ files with the .inp extension.

Files with the .cas extension have the same format as a Gambit .msh file and as such can be renamed to have this extension. These formats are the best route from Gridgen to Simcenter STAR-CCM+. It is important to ensure that the mesh is specified as right-handed in Gridgen before it is exported.

Although Gridgen can export STAR-CD cell/vertex/boundary/input files also, they are not compatible with volume mesh import in Simcenter STAR-CCM+. If you have access to pro-STAR, the files can be read in using the IFILE command and then resaved as a CCM file.

Plot3D Format

and with the following characteristics:

• three-dimensional
• single-block or multi-block
• FORTRAN-unformatted or C-binary

There is no need to specify the characteristics of the file; the importer recognizes the file type and also determines whether byte-swapping is necessary. Simcenter STAR-CCM+ currently does not support two-dimensional, unstructured (tetrahedral), or formatted (ASCII) Plot3D files. Double precision files are now supported.

When you import a Plot3D file, Simcenter STAR-CCM+ can read boundary definitions from a .fvbnd file at the same time, if the .fvbnd file has the same base file name and is in the same directory as the Plot3D file.

Fluent Format

These files have the same format internally, but can be written in text or binary form. Simcenter STAR-CCM+ automatically recognizes a file as being binary or text and imports it without requiring further action.

Also see the guidelines for Migrating from Fluent.

CGNS Format

CGNS files can be used to import both mesh and solution data into Simcenter STAR-CCM+. You can import CGNS meshes containing tetrahedra, prisms, hexahedra, polyhedra, and pyramids. The import of CGNS files in Simcenter STAR-CCM+ is based on the CGNS library version 3.4.1 (64bit). For more information, see CGNS File Import and Export.