  We derive explicit analytic expressions for the lateral force for two
different configurations with corrugations, parallel plates and concentric
cylinders. By making use of the multiple scattering formalism, we calculate the
force for a scalar field under the influence of a delta-function potential that
has sinusoidal dependence in one direction simulating the corrugations. By
making a perturbative expansion in the amplitude of the corrugation we find the
leading order for the corrugated concentric cylinders and the next-to-leading
order for the corrugated parallel plates.
