Abstract
Pontoon-type floating breakwaters have been adopted everywhere in Japan. Especially for improving the ability of reducing transmitted waves for comparatively long waves by the floating breakwater, various studies have been carried out. In this study, to improve the high reflective feature of the pontoon breakwater for comparatively short waves and also to expand the effective range of wave period for the reduction of transmitted waves, we apply the two additional devices to the pontoon breakwater; vertical-barrier-type reflection dissipaters and submerged horizontal plates. The formerd evice is intended to reduce reflected waves from the pontoon for comparatively short waves. The latter is to expand the effective range of wave period. There are two dissipation mechanisms presumed in this model. One is to enhance vortex flows around an outside vertical barrier by the use of piston-mode wave resonance in the water chamber. The other is effective usage of radiated waves by the oscillating floating body, especially for comparatively long waves.
