Trelis 16.4 User Documentation

**Applies to**: Surfaces and
Volumes.

**Summary**: Produces an arbitrary-sided
block primitive mesh for a surface or volume.

To use a polyhedron scheme on a volume or surface

- On the Command Panel, click on
**Mesh**. - Click on
**Volume**or**Surface**. - Click on the
**Mesh**action button. - Enter the values for
**Select Surfaces**or**Select Volumes**. This can also be done using the**Pick Widget**function. - Select
**Polyhedron**from the drop-down menu. - Click on
**Apply Scheme**and then**Mesh**.

Volume <range> Scheme Polyhedron

Surface <range> Scheme Polyhedron

**Discussion**:

The polyhedron scheme is a meshing primitive for 2d and 3d n-sided regions. This is similar to the triprimitive , tetprimitive, and pentagon schemes, except rather than 3, 4, or 5 sides, it allows an arbitrary number of sides. The scheme works best on convex regions. Surfaces must have only one loop, and each vertex must be connected to exactly two curves on the surface (e.g., no hardlines). Volumes must have only one shell, each vertex must be connected to exactly three surfaces on the volume, and each surface should be meshed with scheme polyhedron. There are some interval assignment requirements as well, which should be automatically handled by Trelis.

If the polyhedron scheme is specified for the volume, then the surfaces
of the volume are automatically assigned scheme polyhedron as well, unless
they were hard-set by the user. Schemes should be specified on all volumes
of an assembly prior to meshing any of them. Scheme polyhedron attaches
extra data to volumes; if Trelis is behaving strangely, the user may need
to explicitly remove that data with a **reset volume all**, or similar
command.

Scheme polyhedron was designed for assemblies of material grains, where each volume is roughly a Voronoi region, and the assembly is a periodic space-filling model (tile). Figure 1 shows two examples of polyhedron meshes.