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Mesh From Shape by Gmsh

Mesh Refinement

FEM

Description

The FEM MeshBoundaryLayer command enables the user to set a localized set of meshing parameters by selecting a set of elements (Vertex, Edge, Face) and applying the parameters to it.

It is especially useful for refining meshes close to edges or surfaces in flow simulations. For example, it can be used to refine the mesh in the vicinity of an air foil or obstacle in a flow.

The boundary layer has the advantage of creating highly defined, anisotropic meshes. As the name implies it supports accurate calculations near boundaries, e.g. a wall where friction occurs, generating a velocity gradient.

Usage

1. To enable the command a Mesh From Shape by Gmsh must be provided first.
2. Select the Mesh object in the Tree View.
3. There are several ways to invoke the command:
   • Press the Mesh Boundary Layer button.
   • Select the Mesh → Mesh Boundary Layer option from the menu.
4. Edit the start element size, the growth rate and the number of growth layers.
5. Press the Add button. Select a vertex, edge, face. introduced in 1.1: To remove objects from the selection, press the Remove button.
6. Click the OK button.
7. Close the task.

   Result: You now should see a new FEMMeshBoundaryLayer object under the FEMMeshGMSH object (see example #3 below) in your active analysis container.

8. Double-click on the FEMMeshGMSH parent object in your Model Tree and press Apply to force a mesh recalculation.
9. Close the task.

After the mesh has been created you can change its properties using the Property View. After you changed a property, you must reopen the Gmsh dialog again and click the Apply button. (You can leave the dialog open while changing properties.)

You can create as many different mesh boundary layers as needed.

Visual examples

Example 1: The initial coarse FEMMeshGMSH on a 2D case

Example 2: After applying a Mesh boundary layer

Example 3: A simple example of the resulting Model Tree

Mesh From Shape by Gmsh

Mesh Refinement

FEM