Exporting Fluent Grid Files

Geometry can be exported from Cubit to the Fluent .msh format. This format can be used to exchange grid information between .msh compatible programs including Fluent, GAMBIT, and TGrid. The command used to export the mesh geometry is:

Export Fluent '<filename>' [Surface <id_list>|Volume <id_list>] [Overwrite]

The filename should be enclosed in either single or double quotes. By convention, the file extension .msh is applied to grid files. The extension should be included in the filename section. Other file extensions such as .cas may be used, but they cannot be guaranteed to be compatible with either GAMBIT or TGrid.

In order to guarantee that the grid file will be compatible with Fluent, all bodies must be merged (See Geometry Merging). Several types of Fluent boundary condition zones are now implemented in Cubit. They are:

axis
exhaust fan
fan
inlet vent
intake fan
interface
interior
mass flow inlet
outflow
outlet vent
periodic
periodic shadow
porous jump
pressure far field
pressure inlet
pressure outlet
radiator
symmetry
velocity inlet
wall

Boundary condition zones created in two different ways. The first way involves user-defined mesh groups consisting only of quads (3D), triangles (3D), or element edges (2D) (See Geometry Groups). The second way involves sidesets. Specifying a boundary condition consists of selecting a user-defined mesh group or a sideset, or a surface. Selecting a surface automatically assigns the boundary condition to the sideset associated with that surface. The boundary condition type is specified and is either given a name or an id (See Using CFD Boundary Conditions). Groups or sidesets of mixed type (e.g. hexes and faces) will not be exported. All surfaces not set to one of the first seven boundary condition types are automatically set to type ‘wall’. The various parameters for each of the boundary condition types must be set within either Fluent or GAMBIT.

Cell zones are automatically created for 3D meshes containing blocks. Blocks must contain entire and continuous volumes in order to create a valid grid. In 2D models, the cell zones are created from sidesets containing only quads or tris. In order to create a valid grid, these sidesets must contain whole, continuous surfaces. All cell zones are by default set to type ‘fluid.’

If no entities are specified, the entire model is exported. In order to export selected entities, the types ‘volume’ and ‘surface’ can be specified. In 2D cases, use ‘surface’ while in the 3D case use ‘volume.’

The exporter can handle higher-order elements, although Fluent will convert the elements to first-order upon import.