The Periodic Condition node adds a periodic boundary condition. This periodicity can be continuous (the default) so that u(x0) = u(x1) or antiperiodic so that u(x0) = −u(x1) and can control which dependent variables to which the periodic condition applies.
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The software usually automatically identifies the boundaries as either source boundaries or destination boundaries. This works fine for cases like opposing parallel boundaries. In other cases, right-click Periodic Condition and add a Destination Selection subnode to control the destination. By default it contains the selection that COMSOL Multiphysics identifies. A “read only” Explicit selection node (
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Select a Type of periodicity: Continuity (the default) to make the dependent variables equal, or Antiperiodicity to make them antiperiodic: u(x0) = −u(x1).
For each dependent variable in the PDE, choose to apply the periodic condition by selecting, for example, the Apply condition on variable u1 check box. By default, the periodic condition applies to all dependent variables.
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