Setting Mesh Attributes

Mesh attributes control various aspects of the mesh generation process, including mesh size. Mesh attributes can be set on a global (whole model) and/or local (model entity) basis.

An attribute specification applies to the closure of an entity, so if a size is specified on a model face, the model edges and model vertices on the boundary of the face will inherit the same size specification. However, a separate size specification may be given for the edges and vertices in this case.

There are a number of different ways to specify mesh entity size. The specifications can be absolute sizes, relative sizes, dependent on the curvature of the model, and so on. In all cases each of these specifications are eventually turned into a mesh entity size. If conflicting mesh size specifications are given, regardless of whether they are from the same type of mesh attribute or not, AcuMeshSim will pick the smaller of the resulting sizes. For example, if a size of 1.0 is requested on a given face and a size of 0.1 is requested on an edge of that face, AcuMeshSim will create elements of size 0.1 on the edge and grade the mesh on the face so that it smoothly transitions from a size of 1.0 away from the edge to 0.1 near the edge. However, if a size specification of 0.1 is given on a face and 1.0 is given on an edge of the face, a mesh of 0.1 will be generated for the entire face including all of its edges.

The size specification in AcuMeshSim can be roughly equated to the edge length of the elements that it will generate. It is an average length, in that there will be a normalized distribution of mesh lengths around the requested size. There will be some elements generated that are longer than the requested size, and some that are smaller.

Sometimes geometry will be a limiting factor for mesh edge length. For example, a model edge that is much smaller than the requested mesh size will result in a mesh edge no longer than that model edge.

If no mesh attributes are set a default global mesh size will be set to 1/8 of the length of the largest edge of the bounding box of the model.