Solid CAD Support Forms the Foundation for Meshing
Pointwise's proprietary geometry kernel supports hybrid geometry so that you can work simulataneously with analytic surfaces (NURBS, B-Splines), faceted geometry (triangle mesh as from an STL file) or wireframes as your needs demand. In addition, CAD geometry can be imported from native, neutral, and standard file formats*.
Solid Modeling and Solid Meshing
Sloppy CAD geometry leads to all sorts of meshing troubles and Pointwise's Solid Meshing suite of features is designed to avoid slop from the outset. By forming the CAD geometry into a watertight solid gaps are closed implicitly so that meshing can proceed without a hitch. Pointwise has implemented a broad range of solid modeling operations, some that are performed automatically during CAD file import and others than can be fine-tuned for just a portion of the model.
An important concept in Solid Meshing is the quilt, a subregion of the geometry that reflects the design intent (for example, the hood of a car or the upper surface of a wing) that will be meshed as a single. At its simplest, every trimmed surface is a quilt. Assemble adjacent trimmed surfaces into a larger quilt and you're ready to mesh.
Fault-Tolerant Meshing Eliminates CAD Healing
Another problem with CAD model interoperability is sloppy geometry such as gaps between adjacent surfaces, overlapping surfaces, and missing features. An analyst must be able to mesh a less than perfect model. Even though other software attempts to "heal" the CAD model through a variety of manipulations, healing is an ill-defined problem since design intent is usually unknown.
Using a technique called merging, Pointwise is able to create a fully closed mesh upon a sloppy CAD model. Merging automatically identifies adjacent surface meshes, joins them across CAD model gaps, and uses the mesh solver to remove CAD artifacts such as topology and sliver surfaces from the mesh.
Working with Faceted Geometry
When working with triangular-faceted (such as a VRML, STL, or old mesh file) it's necessary to recover the topology of the geometry so that feature lines (also known as hard edges) are reproduced accurately in the mesh). Pointwise provides feature extraction, the ability to identify feature lines in the faceted data given only a relative turning angle limit between adjacent triangles.
Shell entities (i.e. faceted geometry) can be intersected just like any other geometry entity in the model. They can also be split by cutting them with planes, both constant coordinate planes and any arbitrarily oriented plane you create. Faceted geometry can also be rejoined.
Pointwise does not require the use of a CAD model for meshing - the mesh can be created directly in 3D without having to create geometry first. This feature lessens dependence on the CAD system, allowing the analyst to use CAD geometry only where necessary. Furthermore, Pointwise's geometry modeler may be used to supplement the CAD model and create new models from scratch.
When meshing complex CAD models, Pointwise can create meshes that are independent of the CAD topology. A mesh may span an entire CAD surface, only a portion of a surface, or multiple surfaces.
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*Support for particular entity types varies depending on CAD file format. For example, annotation entities are not supported for the native CAD formats. Entity names are only supported if applied to geometric entities.