Numerical analysis of a 3D floating breakwater performance

In order to investigate the actual performance of an optimized 2D floating breakwater model which is previously obtained by genetic algorithm (GA), the performance and characteristics in terms of wave reflection of the corresponding 3D model of this shape are computed and analyzed. Higher order boundary element method (HOBEM), based on the potential-flow theory and uses quadratic representation for quadrilateral panels and unknown velocity potentials on each panel, is adopted as the main computation method. The hydrodynamic forces, wave-induced body motions, wave elevation on the free surface, and second-order wave drift force are computed at various wavelengths. The accuracy of computed results is confirmed by checking the Haskind-Newman and energy-conservation relations. By extending the longitudinal length of the model in the 3D analysis and comparing the results to corresponding ones in the 2D analysis, 3D effects could be realized and discussed in both cases of fixed and free motions. It is shown that 3D effects on the body motions are not so large in the present case studied but the free-surface wave elevation is spatially three dimensional even near the middle of a longer body.