The dimensions of the base and the fins can be parameterized, as shown on Figure 3-15. In addition, an offset from the base border can be added.

When the thickness of the fins is small in the x direction, the fins can be defined as boundaries instead of solids in order to reduce the size of the model. Indeed, small elements are required to mesh the fins across their thickness in this case. It is done by setting the shell parameter to 1. The default meshes obtained with shell = 0 (left) and shell=1 (right) are shown in Table 3-14 for an example configuration. Setting shell to 1 significantly reduces the number of mesh elements, as shown below.

Note that when shell=1, the X_fins_bottom, Y_fins_bottom, X_fins_top, and Y_fins_top parameters are not used.

A step can be defined in the x direction at the center on the base. The parameter step_width specifies the number of filled gaps from middle to border by the step, as shown on Figure 3-16. This option is not available for shell fins (shell=1).

Finally, a fillet transformation can be applied at the top and bottom of the fins, as shown on Figure 3-17. The fillet transformation at the bottom of the fins is not available for shell fins (shell=1).