If you apply the free meshing technique and tetrahedral element shape to a region, an Insert boundary layer toggle and Assign Controls button are available in the Mesh Controls dialog box.
Adding a boundary layer comprised of multiple layers of wedge elements to a tetrahedral mesh region is most useful for Abaqus/CFD analyses. The boundary layer creates a dense mesh at and near the boundary walls, where fluid flow and temperature are strongly affected by contact and heat transfer with the walls and surrounding conditions.
If you add a boundary layer to multiple meshing cells, Abaqus/CAE temporarily fixes the seeding on any internal faces between the cells to simplify creation of the boundary layer across these faces.
To add a boundary layer of wedge elements:
From the main menu bar, select Mesh
Controls. (For detailed instructions, see “Assigning mesh controls,” Section 17.18.1.)
Note: You must select a free tetrahedral mesh to include a boundary layer of wedge elements.
Toggle on Insert boundary layer near the bottom of the Mesh Controls dialog box, and click Assign Controls.
Abaqus/CAE displays the Boundary Layer dialog box.
Enter the Wall element height.
The wall element height sets the height or thickness of the first layer of wedge elements against the boundary walls.
Enter the Growth factor.
Starting from the wall elements and moving inward, the height of each successive layer is determined by multiplying the height of the previous layer by the growth factor. The growth factor must be between 1.0 and 2.0, inclusive, where 1.0 results in no growth and 2.0 doubles the thickness of each new layer.
Enter the number of wedge element layers in the boundary layer.
Abaqus/CAE displays the total Boundary layer thickness based on your entries in Step 3 through Step 5.
If desired, toggle on Inactive faces, and click Edit to select faces that you do not want to include in the boundary layer.
The inactive faces are expected to be approximately planar and perpendicular to local flow directions or along a plane of symmetry.
Note: The default selection method is based on the selection method you most recently employed. To revert to the other method, click Select in Viewport or Sets on the right side of the prompt area.
If desired, toggle on Create set, and enter a set name to save a set containing all the boundary layer elements.
Click OK to close the Boundary Layer dialog box.
The boundary layer will be created when you mesh the regions.
If mesh generation fails due to problems in the boundary layers, Abaqus/CAE displays a preview of the boundary layer mesh along with a warning dialog box. Before closing the warning dialog and deleting the mesh preview, look for problems such as self-intersecting layers near sharp corners; the possible failure modes are similar to those described for offset meshes in “Reducing element distortion and collapse during mesh offsetting,” Section 64.3.3. Make the necessary corrections to the boundary layer controls and try to mesh the regions again.
