The boundary element method is complementary to the finite element method, which most of AC/DC interfaces are solved with. The boundary element method is sometimes more efficient than other methods, including finite elements, in terms of computational resources for problems where there is a small surface-to-volume ratio. Physics interfaces based on the boundary element method differ from those based on the finite element method in that they only use mesh elements on the boundaries of the modeled regions (curves in 2D and surfaces in 3D). For a detailed discussion, see Theory for the Boundary Elements PDE in the COMSOL Multiphysics Reference Manual.

In the AC/DC Module, The Electrostatics, Boundary Elements Interface and The Magnetic Fields, No Currents, Boundary Elements Interface use the boundary element method.