CAD Topology

For a correct and efficient setup of your simulation, you should make sure that your CAD model has the right topology for the simulation you want to run.

In general, a CAD model consists of different types of topological entities such as solids, faces, edges or vertices. You should be aware of this topology since it will have an impact on how the mesh is generated.

General

Most of the CAD models are described using the B-Rep method, which describes shapes using limits. A B-Rep model is composed of two parts:

  • Topology: Describes how elements are bounded and connected
  • Geometry: Describes the shape of each element

Depending on how you built your CAD model as well as depending on the type of CAD software you are using, the topology of your CAD model might be described differently. For a successful meshing and simulation setup it is of great help to be aware of the topology of your CAD model. That way you will not try to build a volume mesh for a surface model, which in general does not work.

Topological Entities

Solids

To run a simulation based on a volume mesh, your CAD model needs to contain solids. The mesh algorithm will detect them automatically and will be able to create volume meshes for it.

Please note, that a CAD model can contain either one solid (= part) or multiple solids (= assembly). This is relevant for example if you plan to run a structural simulation. If you are dealing with an assembly, each solid will be meshed as a single mesh, such that you need to connect these solids later via contact constraints to get a valid simulation. For a single solid mesh, this will not be necessary.

Faces

A CAD model might also only consist out of faces and no solids at all. This means that you can’t create a volume mesh for such a CAD model.

Edges

More information coming soon.

Vertices

More information coming soon.

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