Use this node to add periodic conditions for the radiative intensity or incident radiation on boundary pairs. The Destination Selection subnode is available from the context menu (right-click the parent node) or from the Physics toolbar, Attributes menu.

For information about the Orientation of Source section, see Orientation of Source and Destination in the COMSOL Multiphysics Reference Manual.

Physics Tab with Radiation in Participating Media or Radiation in Absorbing-Scattering Media selected:
Boundaries>Periodic Condition