Defining Boundary Layers After Meshing

  1. On the ribbon, click Layers .
  2. Click Select face and pick the blocking face(s) that you want to offset. Press the Ctrl key or use the selection filter to determine selection preference.
    Alternatively, click Select body and pick the entire blocking body. Then, click Select target face and pick the block faces that you do not want to offset. This selection process may be simpler for more complex geometries.
    If you are selecting faces for a fluid flow simulation, you typically want to pick faces that represent a wall boundary. For a structural simulation, you typically want to pick faces that represent a boundary where you anticipate high stress, and you want your mesh to have anisotropy so that you can capture the stress gradient near the boundary.
    Tip: For complex models in which multiple faces require boundary layers, or to select internal block faces, you may find the Inverse Selection option from the context sensitive (RMB) menu helpful.
    For surface bodies, the selection processes are similar except you will select block edges instead of faces to offset. If layer modification is required, click Select block edge and pick the internal block edge(s) as shown in the example.
  3. The available Options depend on blocking or geometry selection.
    • For blocking selection:
      • Layer growth method is restricted to Total Thickness.

      • The Offset method is used to specify how the offset layer thickness is calculated. Choose Absolute to force the Offset value to use your model's measurement units. Default is Relative.

      • Specify a numeric Offset value.

      • Enable Link shape to cause the internal edge(s) of the boundary layers to be shaped by the nearest, corresponding geometry shape. This can help make a more uniform height throughout the layer region. However, the edges and mesh in the center block(s) may not be able to smooth away as quickly, resulting in more skewed cells. Default is disabled.

    • For geometry selection:
  4. Click Complete to create the boundary layer control.

The following sequence of images shows the blocking structure for various options on a simple cylinder with disabled and enabled mesh display.

  • The top row shows the basic blocking with no layers. Cells near the vertices on the curved surface are highly skewed.
  • The second row shows the how the blocking is split to accommodate the layers using a Relative offset value of 1.0. Note that boundary layers were created only on the cylinder side faces.
  • In the third row, the split was modified by setting the relative offset value to 0.2.
  • In the bottom row, the layer control was created with Link shape enabled and an offset value of 0.75. (Block cage display is disabled.)