Use Mesh control edges 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 (2D) or on faces (3D), a finer mesh may be required. One way to avoid refining the mesh in the entire domain or face, is to partition it, then assign a finer mesh size to the domain or face created by the partitioning, as shown in Figure 7-40. By designating the created edges as a mesh control edges, they will only be visible in mesh mode, and only before the mesh is generated. As soon as the mesh is built in domains and faces adjacent to the mesh control edges, the designated edges are removed.

The operation removes a selection of edges that are isolated or that are adjacent to precisely two faces (in 3D) or two domains (in 2D, as shown in Figure 7-40). The edges act as a partitioning, and are removed from the geometry, but become available when you build the mesh. Use a mesh control edge to control the element size inside a domain, or to create a mapped mesh in regions, as shown below. Mesh control edges do not change the number of domains (2D) and edges displayed in the physics settings.

An advantage of working with mesh control edges is that when the edges have been removed, the mesher can move mesh vertices to make a smoother the size transition across the removed entities (see Figure 7-41). This behavior is controlled by the settings in the section Control Entities of the mesh operation used to mesh the domains.

To use the operation, in the Geometry toolbar, from the Virtual Operations menu (), select Mesh Control Edges (). Then enter the properties of the operation using the following sections:

Select the edges that you want to use for mesh control in the Graphics window. They then appear in the Edges to include list. If the geometry sequence includes user-defined selections above the Mesh Control Edges node, choose Manual to select edges, or choose one of the selection nodes from the list next to Edges to include.

Click the Active button to toggle between turning ON and OFF the Edges to include selections.

Use the Include adjacent vertices check box to specify if the operation also include the ignorable start and end vertices of the edge.