Boundary Layer Meshing

Boundary layer meshing is best accessed via the GUI.

To create a boundary layer:

1. On the Command Panel, click on Mesh and then Boundary Layer.
2. Click on the Create action button.
3. Select System Assigned ID or manually enter an ID.
4. On the Settings tab, enter the appropriate size for the first row in the boundary layer.
5. Enter a value for the Growth Factor.
6. Specify the Number of Layer.
7. Optionally select Internal Continuity.

   

   Figure 1 - Settings Panel

   First row(a) -- the height of the first layer in the boundary layer

   Growth Factor(b/a) -- the factor by which each layer grows

   Number of Layers -- the number of layers that make up a boundary layer

   Internal Continuity  -- continuity flag for boundary layers.  If on, all intersections are a side type.

8. On the Association tab, select Curve for 2D boundary layers or Surface for 3D boundary layers.

   For 2D boundary layers:

   1. In the Curve ID(s) field, enter the curve ID(s) where the boundary layer(s) begins.
   2. In the Surface ID field, enter the surface ID that contains the boundary layer(s).
   3. Click Add to add the curves to the boundary layer(s).
   4. Click Create to create the boundary layer(s).

   For 3D boundary layers:

   1. In the Surface ID(s) field, enter the surface ID(s) where the boundary layer(s) begins.
   2. In the Volume ID field, enter the volume ID that contains the boundary layer(s).
   3. Click Add to add the curves to the boundary layer(s).
   4. Click Create to create the boundary layer(s).

Figure 2 - Association Panel

For 2d boundary layers, a curve/surface pair is given to create a boundary layer starting from a curve and growing out on the given surface.

For 3d boundary layers, a surface/volume pair is given to create a boundary layer starting from a surface and growing out on the given volume.

Intersection Types

In some cases, the user may want to adjust the intersection types. This could be because the automatic intersection type is not desired, or because it is not workable due to ambiguity.

The four intersection types are:

• end - suitable for angles between 0 and 135 degrees.
• side - suitable for angles between 135 and 225
• corner - suitable for angles between 225 and 315
• reversal - suitable for angles 315 to 360

These intersection types may be set on a vertex/surface basis and on a curve/volume basis.

Figure 3 - Intersections Type Panel

Current Limitations

Not all combinations of intersection types and topology are supported for 3d cases. An end, corner, or reversal may not span multiple curves in a single volume. A possible workaround is to composite the curves to make a single curve.

Not all meshing schemes may be used in combination with boundary layers. In cases where it is not supported, the boundary layer will be ignored in mesh generation.  It is supported with the following schemes:

• trimesh
• pave
• map
• submap
• sweep
• tetmesh.

Underlying Cubit Commands

Create Boundary_layer <id>

Delete Boundary_layer <id>

Modify Boundary_layer <id> add Curve <id_range> Surface <id>

Modify Boundary_layer <id> remove Curve <id_range> Surface <id>

Modify Boundary_layer <id> add Surface <id_range> Volume <id>

Modify Boundary_layer <id> remove Surface <id_range> Volume <id>

"*** Only three of the four parameters should be specified ***

"***           (Height, Growth, Layer, or Depth)           ***

Modify Boundary_layer <id> uniform Height <double> Growth <double> Layers <double> Depth <double>

Modify Boundary_layer <id> continuity {yes | no}

set boundary_layer intersection volume <id> curve <ids> type {end, side, corner, reversal, default}

set boundary_layer intersection surface <id> vertex <ids> type {end, side, corner, reversal, default}

Boundary_layer visibility {on|off}

[set] Boundary_layer <color>

The boundary_layer visibility command toggles the display of boundary layers in the graphics window. The [set] boundary_layer <color> command sets the color used to draw all boundary layers; <color> is any of the recognized Cubit color names.

Sample Journal Files

Example 1

Example 2