6.1 Mesh Topologies

As an unstructured solver, ANSYS FLUENT uses internal data structures to assign an order to the cells, faces, and grid points in a mesh and to maintain contact between adjacent cells. Therefore, it does not require i,j,k indexing to locate neighboring cells. This gives you the flexibility to use the best mesh topology for your problem, as the solver does not force an overall structure or topology on the mesh.

For 2D meshes, quadrilateral and triangular cells are accepted, and for 3D meshes, hexahedral, tetrahedral, pyramid, wedge, and polyhedral cells can be used. Figure  6.1.1 depicts each of these cell types. Both single-block and multi-block structured meshes, as well as hybrid meshes containing quadrilateral and triangular cells or hexahedral, tetrahedral, pyramid, and wedge cells are acceptable. ANSYS FLUENT also accepts meshes with hanging nodes (i.e., nodes on edges and faces that are not vertices of all the cells sharing those edges or faces). See this section in the separate Theory Guide for details. Meshes with non-conformal boundaries (i.e., meshes with multiple subdomains in which the mesh node locations at the internal subdomain boundaries are not identical) are also acceptable. See Section  6.4 for details.

Figure 6.1.1: Cell Types

Some examples of meshes that are valid for ANSYS FLUENT are presented in Section  6.1.1. Different cell shapes and their face-node connectivity are explained in Section  6.1.2. Section  6.1.3 explains how to choose the mesh type that is best suited for your problem.