Periodic Condition
The Periodic Condition node defines periodicity or antiperiodicity between two boundaries. If required, activate periodic conditions on more than two boundaries, in which case the Periodic Condition tries to identify two separate surfaces that can each consist of several connected boundaries. For more complex geometries, it might be necessary to use the Destination Selection section, which you activate by right-clicking the Periodic Condition node and select Manual Destination Selection. With that section, the boundaries which constitute the source and destination surfaces can be manually specified.
When this feature is used in conjunction with a Sector Symmetry feature on connected boundaries, wherever the sector symmetry boundaries connect with the periodic boundaries, the same periodic condition feature cannot be used on both sides. At least two periodic condition features are required for the model to compute correctly.
Boundary Selection
The software usually automatically identifies the boundaries as either source boundaries or destination boundaries, as indicated in the selection list. This works fine for cases like opposing parallel boundaries. In other cases, right-click Periodic Condition and select Manual Destination Selection to control the destination. By default it contains the selection that COMSOL Multiphysics identifies.
When using nonconforming meshes on the source and destination of a periodic boundary pair, for numerical stability, a finer mesh should be applied on the destination side. Use conforming meshes if possible.
Destination Selection
This section is available for specifying the destination boundaries, if needed, when the Manual Destination Selection option is selected in the context menu for the Periodic Condition node. You can only select destination boundaries from the union of all source and destination boundaries.
Periodic Condition
Select a Type of periodicity — Continuity (the default), Antiperiodicity, or Floquet periodicity. Select:
•
Continuity to make the potential periodic (equal on the source and destination).
•
Antiperiodicity to make it antiperiodic.
•
Floquet periodicity (only available with products supporting piezoelectric modeling). Specify the components of the k-vector for Floquet periodicity kF (SI unit: rad/m).
Constraint Settings
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box.
Orientation of Source
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box. For information about the Orientation of Source section, see Orientation of Source and Destination in the COMSOL Multiphysics Reference Manual.
Orientation of Destination
This section appears if the setting for Transform to intermediate map in the Orientation of Source section is changed from the default value, Automatic, and Advanced Physics Options is selected in the Show More Options dialog box. For information about the Orientation of Destination section, see Orientation of Source and Destination in the COMSOL Multiphysics Reference Manual.