Why Hybrid Grids
Traditional approaches to mesh generation have been
via block-structured (usually composed of hexahedra) or unstructured
(tetrahedra) methods. There are pros and cons to both approaches and thus the
strategy chosen has been dependent on the particular application. CENTAUR combines the
best of both methods via a hybrid
(prismatic/hexahedral/pyramidal/tetrahedral) meshing strategy. The prismatic and
hexahedral elements are used in regions of high solution gradients, and
tetrahedra are used elsewhere. Pyramids are used in some locations to allow for the transition between the prisms/hexahedra and the tetrahedra. Hybrid Grid Advantages:
- The prismatic or hexahedral layers close to wall surfaces exhibit good
orthogonality and clustering capabilities, characteristics of structured mesh
- The structured nature allows for the implementation of multigrid convergence
acceleration schemes, implicit methods, and also results in memory savings.
- The use of tetrahedra to fill the rest of the domain allows single-block
generation for extremely complex geometries since the tetrahedron is the simplest
- The tetrahedral elements are well suited for grid refinement.
- The flexibility of the hybrid mesh generation approach automates an
otherwise highly interactive procedure.
- The hybrid prismatic/hexahedral/tetrahedral strategy requires no solution
interpolation or grid interfacing techniques as in the traditional
- The prismatic and hexahedral portions of the grid require less memory than a tetrahedral grid of the same resolution.
- Generation of the prisms and hexahedra is faster than the generation of tetrahedra.