Creating faces from existing meshes by selecting meshes

You can use the Face from Mesh command to create faces from both manifold and non-manifold 2D meshes and from certain types of 3D meshes and 3D element faces.

Selecting the mesh

When you create new faces from an existing 2D or 3D mesh, the mesh you select must meet the following conditions:

• The mesh cannot be associated to any geometry.

• A 3D mesh can contain linear or parabolic tetrahedral or hexahedral elements only.

• The mesh cannot contain duplicate nodes. Use the Duplicate Nodes command to identify and eliminate any duplicate nodes and then select the Face from Mesh command.

• As a best practice, the mesh should have consistent element normals. However, you can use the Allow Inconsistent Element Normals option in the Face from Mesh dialog box to control whether to try to create a face if the mesh normals are inconsistent.

The software issues a warning message if the mesh you select is attached to any solid elements. Solid elements could constrain a face generated by the Face from Mesh command from updating. However, if the selected mesh is simply a surface coat of elements and you plan to create a face from that mesh to apply boundary conditions, for example, you can ignore the warning.

Face creation parameters

The options in the Face from Mesh Parameters group let you control how the software creates faces from the selected mesh or meshes.

• The Element Face Feature Angle option controls the locations at which the software creates feature edges. Defines the maximum angle value between the normals on adjacent element faces. The software uses this value to determine whether to create a polygon edge at that location.

• The Element Edge Feature Angle option controls the locations at which the software creates vertices between edges in the new face. You can adjust this value to modify where the software creates vertices.

• The Keep Internal Edges check box controls whether the software retains any scar edges in the interior of the mesh in the new face. Scar edges can touch the boundary of a new face or be entirely interior to the face.

Tip:

You can click Preview Edges to see the feature edges that the software detects automatically based on the current settings. If you are not satisfied with the previewed face, adjust the parameter values and preview the face again.

Face creation process

The software evaluates the elements in the selected mesh to determine how to create the faces. Internally, the software categorizes elements based on whether:

• They have free edges.

• They have an edge that is shared by more than two elements (non-manifold element edge).

• The angle between adjacent elements is greater than the specified Element Face Feature Angle value.

The software then groups elements into logical areas and creates a separate polygon face for each logical area as well as the appropriate polygon edges and vertices. The software then stitches those faces together.

In some cases, the software may create faces that require that you manually modify them before you can remesh them. The software places these faces in a Complex Faces created group in the Simulation Navigator.

Polygon body creation

How the software creates polygon bodies for the new faces depends upon whether the stitched faces are manifold or non-manifold.

• The software places all new manifold faces in a single, new polygon body.

• The software places non-manifold faces in a separate non-manifold polygon body or into multiple bodies.For an open shell mesh, the software creates separate polygon sheet bodies, depending on the nature of the selected non-manifold meshes. For example, in the graphic below, the software created three separate polygon bodies that are stitched at the non-manifold junctions from the non-manifold meshes.For a closed shell mesh, such as a partitioned block that contains a non-manifold face in the interior, the software creates a minimal number of polygon bodies, including polygon sheet bodies, if appropriate.

Where do I find it?

Application	Pre/Post
Prerequisite	A FEM file active
Command Finder	Face from Mesh
Menu	Model Cleanup→Face from Mesh

Learn more

Creating faces from existing meshes

Creating a face from a mesh by selecting elements

Modifying faces created from existing meshes

Face from Mesh example: Connecting a legacy mesh to new geometry

Face from Mesh example: Remeshing a portion of your model

Creating faces from existing boundaries

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Related Topics

Generating surface wrap bodies and meshes

Creating faces from existing meshes by selecting meshes, Simcenter 3D 2021.1 Series

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