Ansys ICEM CFD supports four different methods for generating the tetrahedral volume mesh. They are listed as Tetra/Mixed as each method includes the option of adding boundary layer prism elements. See Tetra/Mixed Mesh Type in the Ansys ICEM CFD Help Manual for more information on these methods.
The Robust (Octree) method generates a volume mesh using a top-down approach, then the mesh is made conformal to the geometry and a patch-independent surface mesh is created at all of the boundaries and internal walls. This method supports several options as describe in Robust (Octree). The process is described in detail on the next page.
The Quick (Delaunay) and Smooth (Advancing Front) methods are bottom up, requiring an existing closed surface mesh to start. If one has not yet been created, ICEM CFD will create the surface mesh from the geometry. Both methods support several options as described in Quick (Delaunay) and Smooth (Advancing Front). Choose a method based on your speed and quality priorities.
Tip: Expert users often use the Robust approach to generate a surface mesh and then regenerate the volume mesh using one of the bottom-up approaches.
The Fluent Meshing method uses Ansys Fluent, in batch, to generate the tetrahedral volume mesh from an input surface mesh, volume mesh or geometry. If no surface mesh input is specified, it will be computed before the Fluent batch process is started. This method is similar to the Quick (Delaunay) method with additional options for prism layers and/or hexahedral elements in the core. The pre inflation prism option first creates the boundary layers from the surface mesh and then fills the remaining volume with tetrahedrons, or optionally, hexa elements. The post inflation prism option replaces tetra elements at the surface with prisms and is more familiar to ICEM CFD users. Each prism option has advantages, and you should not expect the same results from both algorithms. Fluent Meshing inflation also allows part-by-part inflation parameter control.
Global volume fill parameters for this method are described and set using the Fluent Meshing DEZ. Both pre inflation and post inflation prism options use most of the same parameters, which are set using the Prism Meshing Parameters DEZ. Options presented when the mesh is computed include pre inflation or post inflation selection and the hexa-core option.
Important: If enabled, the prisms are grown from a shell mesh (input or created) with the direction of growth determined by the geometry. If no geometry is available, pure tetra meshing will be done without inflation. If the input mesh is a surface mesh, the volume(s) should be marked by material point(s).
Note: Fluent Meshing option for Tetrahedral Mesh Method is available, only when you have a license key that enables Fluent Meshing. The Fluent Meshing option does not work for ansys, mech_2, mech_1, preppost and dyna license keys.