Generation of Semi-Structured Meshes
over Generalized Extruded Volumes

Daniel Rypl

Department of Mechanics
Faculty of Civil Engineering
Czech Technical University in Prague
Thákurova 7, 166 29 Prague, Czech Republic



Abstract:

Sweeping is a common method for the generation of structured and semi-structured meshes over extrusion volumes. Traditional sweeping techniques are based on propagating a surface mesh layer by layer along a particular control curve. Each layer of the extruded mesh is thus bounded by the same surface mesh, possibly subjected to rigid body motion. The present work enhances the traditional method by considering geometrical evolution of the extruded surface mesh during the sweeping. Thus each layer of the resulting mesh is bounded by meshes that are still topologically identical but geometrically only similar. This enables to generate semi-structured meshes over generalized extrusion volumes formed by two opposite geometrically similar and topologically identical cap surfaces and set of lateral quad-mappable surfaces. The source cap surface is discretized by an appropriate unstructured surface mesh which is projected onto the target cap surface using an affine mapping defined between the parametric spaces of the cap surfaces. This mapping is established by a least-squares fit of boundary nodes on the target surface. The structured quad meshes on lateral surfaces are obtained by transfinite interpolation. The volume interior nodes used to form inner layer of elements are defined by the mapping derived from a least-squares approximation of all boundary nodes. The obtained mesh is then subjected to a specific two-phase smoothing.