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.

To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box.

The Constraint settings can be set to Pointwise constraints (default) or Weak constraints. Select Weak constraints to replace the standard constraints with a weak implementation.

Physics tab with Radiation in Participating Media or Radiation in Absorbing-Scattering Media selected: