Diffraction force

The diffraction force is the wave-exciting force arising from the scattering of incident waves by the hull held fixed, that is, the part of the exciting force additional to the undisturbed-wave (Froude-Krylov) pressure force. In linear seakeeping the total wave exciting force is the sum of the Froude-Krylov force, computed from the incident-wave pressure integrated over the wetted hull, and the diffraction force, computed from the scattered potential that satisfies the body boundary condition. It is solved together with the radiation problem by strip theory or three-dimensional panel methods, and is most important for short waves relative to ship length where the hull strongly disturbs the incident field.