Reduction effect of a submerged-plate toward wave exciting forces acting on a very large floating structure

A new type VLFS using Submerged Plates (Sub-Plate VLFS) has been proposed for extending the operational area of VLFS to deeper sea with reducing environmental problems. The system consists of a Floating Breakwater using Submerged Plate (FBSP) and a VLFS with submerged plate. FBSP not only decreases incident wave height for VLFS but also generates a steady flow, which enhances the exchange of seawater around VLFS; thus very friendly to sea environment. This time, we focus on the submerged plate built into the VLFS with the partial openings with 5 m long, which enables the reverse flow on the plate. First, we have carried out the extensive experiments to make clear the characteristics of the wave exciting forces and moments acting on the submerged plate and the fore part of VLFS. Then, we perform the numerical simulations by applying the Marker and Cell method (MAC method) and compare with the experimental results. We discuss the validity of MAC method and the effect of the submerged plate on the hydrodynamic forces and moments acting on the fore part of VLFS. As the result, we get the conclusion that the submerged plate is useful for reducing the wave exciting forces and moments on the structure behind the submerged plate.