**Wedge**

In cylindrical polar coordinates, the cylinder is a surface of constant radial coordinate *r*, while a wedge is the surface of constant angular coordinate θ.

Interaction between a tilted wedge and a plate:

"Casimir force between sharp–shaped conductors,"

M.F. Maghrebi, S.J. Rahi, N. Graham, T. Emig, R.L. Jaffe, & M. Kardar, preprint (2010)

Highly accurate analytical expressions can be obtained by a multiple-reflection series.

E.g., for the knife edge,

Other interesting limits:

Butterfly:

Dark side of the moon: