Mesh Control Vertices
Use Mesh control vertices for precise control of the mesh in specific regions of the geometry, without affecting the geometry used for assigning physics.
To fully resolve the gradients in a field in certain regions of a domain, on a boundary, or along an edge, a finer mesh may be required. One way to avoid refining the mesh in the entire domain, is to add a point, then assign a finer mesh size to the point, as shown in Figure 7-44. By designating the created point as a mesh control vertex, it will only be visible in mesh mode, and only before the mesh is generated. As soon as the mesh is built inside the domains, on the boundaries, or on the edges adjacent to the point, the mesh control vertex is removed.
Figure 7-44: Point highlighted in blue is designated as a mesh control vertex, which means that the point is removed and is only available when building the mesh. The image on the right hand side shows the geometry after the Mesh control vertices operation has been built, which is the geometry displayed in physics settings. The bottom image shows the resulting mesh where the vertex have been removed.
The operation removes the selected vertices that are isolated or are adjacent to precisely two edges. This is done by ignoring the vertices and composing the adjacent edges, as shown in Figure 7-44 and Figure 7-45. All edges in the geometry must have distinct start and end points. The software will ensure this by preserving or inserting extra vertices on the composite edges, if necessary. The vertices become available when you build the mesh. This makes it possible to partition a face or an edge to prepare it for swept meshing, or to control the mesh size in a specific region, without modifying the geometry that appears when assigning physics settings.
An advantage of working with mesh control vertices is that when the vertices have been removed, the mesher can move mesh vertices to make a smoother the size transition across the removed entities (see Figure 7-45). This behavior is controlled by the settings in the section Control Entities of the mesh operation used to mesh the edges, faces, and domains.
Figure 7-45: Comparing meshes where the Mesh control vertices has been used vs. not used. A vertex added for the purpose of resolving the mesh close to the vertex (highlighted in blue in the image to the left). Designating the vertex as a mesh control vertex removes the vertex and composes the adjacent edges (upper right image). The lower right image shows the mesh if the vertex is not marked as a mesh control vertex. This means that the face and edge partitioning are preserved. Compare the meshes on the right hand side to see the effect of smoothing the size transition across removed mesh control entities.
To use the operation, in the Geometry toolbar, from the Virtual Operations menu (), select Mesh Control Vertices (). Then enter the properties of the operation using the following sections:
Input
Select the vertices (points) that you want to use for mesh control in the Graphics window. They then appear in the Vertices to include list. If the geometry sequence includes user-defined selections above the Mesh Control Vertices node, choose Manual to select vertices, or choose one of the selection nodes from the list next to Vertices to include.
Click the Active button to toggle between turning ON and OFF active Vertices to include selections.