To proceed from geometry and parts to a completed mesh requires two steps:
Set up Mesh Parameters
You should specify mesh size, type, and method along with several type- and method-specific controls. The parameters can be applied globally and individually to parts, surfaces, curves, or regions. Rotational and translational periodicity is also supported.
Compute the Mesh
Meshing methods available include the following:
- Tetra
The Ansys ICEM CFD Tetra mesher takes full advantage of object-oriented, unstructured meshing technology. With no tedious up-front triangular surface meshing required to provide well-balanced initial meshes, Ansys ICEM CFD Tetra works directly from the CAD surfaces and fills the volume with tetrahedral elements using the Octree approach. A powerful smoothing algorithm provides good element quality. Options are available to automatically refine and coarsen the mesh both on the geometry and within the volume.
Also included are a Delaunay algorithm and an Advancing Front algorithm to create tetras from an existing surface mesh and also to give a smoother transition in the volume element size. The Delaunay method is robust and fast; while the advantage of the Advancing Front method is its ability to generate a smoothly transitioning Tetra mesh with a controlled volume-growth ratio.
- Prism
Ansys ICEM CFD Prism generates hybrid meshes consisting of layers of prism elements near the boundary surfaces and tetrahedral elements in the interior for better modeling of near-wall physics of the flow field. When compared to pure tetrahedral meshes, this results in smaller analysis models, better convergence of the solution, and better analysis results.
- Hexa
The Ansys ICEM CFD Hexa mesher is a semi-automated meshing module that allows rapid generation of multi-block structured or unstructured hexahedral volume meshes. ICEM CFD Hexa represents a new approach to mesh generation where the operations most often performed by experts are automated and made available at the touch of a button. Blocks can be built and interactively adjusted to the underlying CAD geometry. This blocking can be used as a template for other similar geometries for full parametric capabilities. Complex topologies, such as internal or external Ogrids, can also be generated automatically.
- Hybrid Meshes
The following types of hybrid meshes can also be created:
Tetra and Hexa meshes can be united (merged) at a common interface in which a layer of pyramids is automatically created to make the two mesh types conformal. These meshes are suitable for models where it is preferred to have a "structured" hexa mesh in one part and is easier to create an "unstructured" tetra mesh in another more complex part.
Hexa-Core meshes can be generated where the majority of the volume is filled with a Cartesian array of hexahedral elements essentially replacing the tetras. This is connected to the remainder of a prism/tetra hybrid by automatic creation of pyramids. Hexa-Core allows for reduction in number of elements for quicker solver run time and better convergence.
- Shell Meshing
Ansys ICEM CFD provides a method for rapid generation of surface meshes (quad and tri) for both 3D and 2D geometries. Mesh types can be All Tri, Quad w/one Tri, Quad Dominant, or All Quad. The following methods are available:
Mapped based shell meshing (Autoblock): Internally uses a series of 2D blocks, resulting in a mesh that aligns better with the geometry curvature.
Patch based shell meshing (Patch Dependent): Uses a series of "loops" that are automatically defined by the boundaries of surfaces and/or a series of curves. This method gives the best quad-dominant quality and capturing of surface details.
Patch independent shell meshing (Patch Independent): Uses the Octree method. This is the best and most robust method for use on an unclean geometry.
Shrinkwrap: Used for a quick generation of a mesh. As it is used as the preview of the mesh, hard features are not captured.
Complete descriptions of the meshing processes are included in subsequent chapters.