Axial Symmetry
The Axial Symmetry node is automatically added to 2D axisymmetric models. The options available for the feature are the same as for Wall, except as follows.
The Boundary Selection is locked and is only applicable to edges on the symmetry axis. The only wall conditions available are Specular reflection (the default), Freeze, Stick, and Disappear. In addition, the Primary Ray Condition section is not included. The Axial Symmetry boundary condition does not affect ray intensity or polarization, except to introduce a phase delay of π in reflected rays to compensate for the change in the principal curvature direction.
The Axial Symmetry condition only applies to straight boundaries that are both on the axis of symmetry and adjacent to a domain in the selection of the physics interface. If rays are propagating in the void region outside of the selected domains, it is possible for the rays to enter the region where r < 0, even though no geometry is defined there.
To ensure that rays cannot propagate into the region where r < 0, draw line segments on the parts of the symmetry axis where no geometric entities exist, then add the Wall node to these edges. Keep in mind that rays can only be subjected to boundary conditions if the corresponding boundaries are meshed.