Numerical And Experimental Investigation Of The Performance Of The Rectangular Floating Breakwater With Horizontally Extended Baseplates

Floating breakwaters have advantages in terms of low cost,easy installation,enviromental friendliness,mobility and low requirements on bottom foundation.Especially in coastal areas with a high tidal range or deep water depth,floating breakwaters may be the only viable option.The pontoon-type floating breakwaters have simple structure which is efficient in moderate wave conditions.In order to improve the performance of the pontoon-type floating breakwaters,especially in long wave conditions,researchers have proposed various modified forms profile,such as the porous floating breakwater,the rectangular floating breakwater with pneumatic chambers,the ?-type breakwates,the pontoon-plate floating breakwaters(the horizontal plate are not fiexd on the bottome of the box.)and so on.This paper presents a new improved potoon-type floating breakwater: the rectangular breakwater with two baseplates protruding horizontally outward.At first,the paper study analytically the wave field of the rectangular breakwater with two baseplates protruding horizontally outward.The analytical method is presented to analyze the radiation and diffraction of water waves by the potoon-type floating breakwater and the new proposed one.Secondly,based on a two dimensional linear water wave theory,the boundary element method is developed to study the radiation and diffraction promblem of a floating arbitrary structure.The added mass,damping coefficients,wave exciting force,transmission and reflection coefficients will be calculated.This paper focuses on the numerical processing of two dimensional radiation condition.Model experiments have also been carried out in order to validate the numerical model for the proposed one.Finally,combining waters condition in South China Sea,the spectral analysis method are applied to study the relationship between the size of floating breakwaters and the transmission coefficient.