Creating a 2D mesh on faceted or convergent geometry

Use the 2D Mesh from Facets command to automatically generate a surface mesh on convergent or faceted geometry that may be too complex to mesh with other commands. Meshing commands, such as 2D Mesh, generally use algorithms that mathematically flatten surfaces to generate the 2D elements. However, convergent polygon geometry can be difficult to mesh using traditional approaches because it often:

• Does not have well defined face boundaries.

• Includes complex, high genus faces that the software cannot easily flatten.

You can use the 2D Mesh from Facets command to automatically generate a mesh of linear or parabolic triangles directly from the facet geometry. The software does not flatten the geometry, and it only performs limited geometry abstraction during the meshing process, depending on the value that you specify for the Small Feature Tolerance.

Types of geometry

You can use the 2D Mesh from Facets command to generate a mesh on the following types of geometry:

• Convergent or standard polygon bodies

• Polygon faces created by the Face from Mesh command

Meshes on neighboring faces

Unlike other meshing commands, the 2D Mesh from Facets command does not preserve any existing meshes that are adjacent to the selected faces. If the software detects adjacent meshes, you can either cancel the mesh or choose to proceed. If you proceed, the software deletes the existing meshes and changes the status of their recipes in the Simulation Navigator to Update Pending.

After the 2D Mesh from Facets command generates the 2D mesh, you can then use the Update Finite Element Model command to recreate the meshes on the adjacent faces. If you use 2D Mesh from Facets to generate a triangular mesh on the outer skin of a solid body, you can also then use the 3D Tetrahedral Mesh command to generate 3D elements in the body.

Edge and surface proximity element size variation

You can use the Surface Proximity Based Size Variation and Edge Proximity Based Size Variation options to control whether the software refines the mesh in regions where gaps between surfaces or between edges on surfaces occur.

For more information, see Surface and edge proximity settings with 2D Mesh from Facets.

Small feature abstraction

Facet geometry may contain small features that can either complicate 2D mesh generation or that can result in unwanted small features in the 2D mesh. You can use the Small Feature Tolerance option to specify a tolerance value for removing those small features. When you specify a Small Feature Tolerance value greater than zero, the software:

• Collapses short facet edges.

• Merges sliver facet faces with adjacent facet faces.

Removing small features from the facet geometry before you generate a 2D mesh can result in a higher mesh quality.

Geometry association

The 2D Mesh from Facets command creates a new mesh that is associated to the underlying geometry. If the underlying part geometry changes, the software updates the mesh. The software stores meshes created with the 2D Mesh from Facets command in a new 2d_mesh_from_facets node in the Simulation Navigator.

You can use the 2d_mesh_from_facets node to modify an existing 2D Mesh from Facets mesh.

Limitations

The 2D Mesh from Facets command does not offer the robust control that is supported by the 2D Mesh command. You can use the 2D Mesh from Facets command together with the 2D Mesh command, but there are some limitations. The 2D Mesh from Facets command:

• Does not honor the location of mesh points.

• Honors only the Size on Face, Size on Edge, and Bounding Volume types of mesh controls. It ignores all other types of mesh controls.

• Does not honor frozen mesh boundaries. As a result, the software:Marks adjacent faces that you mesh with the 2D Mesh command for update when create or update a mesh with the 2D Mesh from Facets command.Updates faces that you mesh with the 2D Mesh from Facets command before it updates faces that you mesh with the 2D Mesh command.

• Creates parabolic elements with straight edges only. If you modify the elements' order and set the Midnode Method list to Curved or Mixed, the software still creates the elements with straight edges.

• Ignores Free Coincident type of mesh mating conditions.

Where do I find it?

Application	Pre/Post
Prerequisite	A FEM file as the displayed part and work part
Command Finder	2D Mesh from Facets

Quick links

Command reference

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Creating a 2D mesh on faceted or convergent geometry, Simcenter 3D 2021.1 Series

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