Radiation and diffraction problems of a floating body in a two-layer fluid of finite depth

A linearized 2-D radiation and diffraction problems are considered of a general-shaped floating body in a two-layer fluid of finite depth. A boundary integral-equation method is developed for solving directly the velocity potential on the wetted surface of a body which straddles both of the upper and lower layers as a general case. For this method, appropriate time-harmonic Green's functions are derived, and an efficient numerical method of evaluating those functions is proposed. Based on the Green's theorem, various hydrodynamic relations for the case of finite depth are derived theoretically, and those relations are confirmed to be satisfied very accurately by the results of numerical computation. Experiments are also carried out by use of water and iso-paraffin oil as the two-layer fluids and a Lewis-form body. Measured results of the added mass, the damping coefficient, and the wave-exciting force are compared with computed results, and favorable agreement is found.