A new method which simplifies the calculation of higher-order hydrodynamic forces is proposed. Solving the integral equation on boundary surfaces including the free-surface by this method, the non-linear terms on free-surface may be directly computed.
Making use of this method, the diffraction potentials are calculated up to the second-order terms in two-dimensional problem.
Results obtained are as follows :
(1) The numerical results by the method agree well with existing results in radiation and diffraction linear problems.
(2) Second-order diffraction forces due to non-linear free-surface boundary condition is nearly proportional to the wave-number of incident wave.
(3) Total second-order diffraction forces computed by the method show good coincidence with the experimental results.