Constriction and Corner Permeances for Finite Domains

The known formulas for two-dimensional "corner" and "constriction" permeances, which were derived by using conformal mappings for infinite domains, can be applied only for large enough domains. In this paper, we analytically solve the problem for finite domains and propose new exact and approximate formulas. We show that, for finite domains, the corner and constriction permeances can be much smaller than for infinite dimensions, and we determine the limits of applicability of simple exact formulas. This offers the possibility to make more accurate analytical calculations of magnetic devices and better evaluate acting magnetic forces