GuiCommand:Container| {{GuiCommand Name: FEM MeshBoundaryLayer MenuLocation: Mesh , FEM mesh boundary layer Workbenches: FEM_Workbench SeeAlso: FEM_tutorial }} {{GuiCommandFemInfo Solvers: All }}
FEM MeshBoundaryLayer
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
-
To enable the function a mesh must be first provided
FEM mesh from shape by Gmsh.
- Select the Mesh object in the Model Tree and press the
FEM mesh boundary layer button.
- Select the Mesh object in the Model Tree and select the Mesh →
FEM mesh boundary layer option from the menu.
- Select the Mesh object in the Model Tree and press the
-
Edit the start element size, the growth rate and the number of growth layers.
-
Select a vertex, edge, face.
-
Click the OK button.
-
Close the task.
: Result: You now should see a new
FEMMeshBoundaryLayer
object under theFEMMeshGMSH
object (see example #3 below) in your active analysis container. -
Double-click on the
FEMMeshGMSH
parent object in your Model Tree and press Apply to force a mesh recalculation. -
Close the task.
After the mesh has been created you can change its properties using the property editor. 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
![](https://raw.githubusercontent.com/FreeCAD/FreeCAD-documentation/master/wiki/images/FEMMeshBoundaryLayer_Example1.png.png)
![](https://raw.githubusercontent.com/FreeCAD/FreeCAD-documentation/master/wiki/images/FEMMeshBoundaryLayer_Example2.png.png)
![](https://raw.githubusercontent.com/FreeCAD/FreeCAD-documentation/master/wiki/images/FEMMeshBoundaryLayer_Example3.png.png)
Notes
Related
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This page is retrieved from https://github.com/FreeCAD/FreeCAD-documentation/blob/main/wiki/FEM_MeshBoundaryLayer.md