About Swept Meshes

A Swept mesh is an example of a semistructured mesh since it is structured in the sweep direction and can be either structured or unstructured orthogonally to the sweep direction. The swept mesher operates on a 3D domain by meshing or reusing an existing mesh on a source face, and then sweeping the resulting face mesh along the domain to an opposite destination face.

You can use several connected faces as source faces. Also the destination can consist of several faces, as long as each destination face corresponds to at least one source face and each source face corresponds to exactly one destination face. Each face about a domain that is to be operated on by the swept mesher is classified as either a source face, a destination face, or a linking face. The linking faces are the faces linking the source and destination faces (see Figure 8-2). The swept mesher can handle domains with multiple linking faces in the sweep direction.

The linking edges are the edges, or the chains of edges, connecting the source and destination faces. For a domain to be possible to sweep, there must be at least one linking edge or chain of edges.

Figure 8-2: Classification of the boundaries about a domain used for swept meshing.

You can specify the source and destination faces manually, but in most cases the swept mesher can automatically identify source and destination faces from the geometry.

• If the source faces are not meshed prior to the sweeping operation the Swept node automatically creates a quadrilateral (or triangular) mesh before sweeping it to the destination. • If the source faces contain a triangular mesh the resulting swept mesh consists of prism elements. • If the source faces contain a quadrilateral mesh the resulting swept mesh consists of hexahedral elements.

The default is to create a quadrilateral face mesh but, depending on the source faces, that is not always possible.

For the sweeping technique to work, the geometry must satisfy these criteria:

•	Each domain must be bounded by one shell; that is, a domain must not contain holes except if they penetrate both the source and destination face.

•	The source and destination for a domain must be opposite each another in the domain’s topology.

•	Each destination face must correspond to one or more source faces.

•	Each source face must correspond to precisely one destination face or a subset of it.

•	The cross section along the direction of the sweep for a domain must be topologically constant.

Coincident source and destination faces are allowed.

If any of the faces about a domain is meshed prior to the sweeping operation, the following must be fulfilled. • If the source and destination faces are meshed, these meshes must match. • Structured quad meshes must be applied to the linking faces.

Swept and Generating a 3D Swept Mesh