CAD readers and geometry construction

Geometries can either be created from scratch or be imported. GAMBIT supports all common standard and native CAD formats. In the examples illustrated below, a native Pro/Engineer part (.prt) is read-in (no translation). The examples show a simple pipe, representing the inlet, created using volumetric primitives and Boolean operators.

Creating the flow domain

The two geometries are connected together using operations like edge projection, face creation and connection. A small design change can be accomplished using new advanced covering technology. The outlet is extended using simple sweep commands.

Flow volume extraction and cleanup

The internal flow volume is easily extracted by indicating the inlet and outlet faces and all remaining external faces are removed. The cleanup tool is used to remove details which commonly create highly skewed cells (circled in red below) like short edges, acute angles and sliver faces.

Decomposition

Cooper meshing is recommended along the pipes since it provides the best accuracy at the lowest cell count. For this decomposition a volumetric primitive, a cylinder, was used. A number of additional commands, in the form of "plugins" are available on www.fluentusers.com. Among them is a new general face split tool, which is used to decompose the volume at two locations (circled in red below).

Edge and surface meshing

The mesh density variations along the pipes are controlled using edge meshing. In the cross-sectional direction structured and unstructured quad meshing is used. In more complex areas an unstructured triangular mesh can be automatically distributed using curvature and proximity size functions.

Boundary layer and volume meshing

Pipes are meshed with high quality stretched hexahedra cells using the unique Cooper volume meshing tool. The boundary layers in the pipe intersection region are previewed before the final unstructured meshing. The volumetric size tetrahedral distribution is directly controlled using size functions, and the non-conformal interface between tet and hex mesh results in the highest quality at a minimum cell count.