Numerical Research On The Hydrodynamic Characteristics Of The Vertical Plate Floating Breakwater

Floating breakwaters are hydraulic structures used to protect coasts,ports and marine structures from waves attacks.Since the engineering cost and construction difficulty of traditional bottom-type breakwaters will increase rapidly with the increase of water depth,the cost and construction difficulty of floating breakwaters are less affected by the depth of water,with the continuous exploration into the deep sea,the floating breakwater has attracted more and more attention.In this paper,by changing the structure of the floating breakwater,the vertical plate is installed on the bottom of the box breakwater to reduce the transmission of waves.In this paper,the physical model test of this floating breakwater with vertical plates is carried out,and the validity of the numerical model is verified through the test.Finally,the ANSYS-AQWA hydrodynamic numerical software is used to analyze the hydrodynamic characteristics of the floating breakwater under the coupling action of regular waves,irregular waves and wave-current.The research results show that:(1)The transmission coefficient of the floating breakwater with vertical plates under the action of regular waves decreases with the increase of draft,vertical plate height and relative width,that is,the wave absorbing performance of floating breakwaters is improved accordingly.(2)The increase of the vertical plate can also greatly reduce the tension of the chain.The tension of the chain when the relative vertical plate height S/h=0.54(0.35m)under the full load condition is 41% of that under the condition without the vertical plate.(3)The pressure changes law of the floating box and vertical plate of the floating breakwater is similar to the anchor chain tension,the pressure decreases with the increase of the draft,the height of the vertical plate and the relative width.(4)Under the action of irregular waves,the transmission coefficient of the floating breakwater with vertical plates decreases with the increase of draft,vertical plate height and pontoon width,and decreases with the decrease of wave period,namely,the wave-eliminating performance of floating breakwaters is improved accordingly.When the flow velocity is 0.8m/s,compared with the case of waves,the transmission coefficient increases by 0.2 and the wave suppression performance decreases by 29%.The vertical plate is added to the floating breakwater.Under the full load condition,the vertical plate height is S/h=0.23.Compared with S/h=0,the transmission coefficient is reduced by 0.24,and the wave suppression performance is improved by 30%.(5)The tension value of the anchor chain of the floating breakwater with vertical plates increases with the increase in draft depth,wave period,flow velocity and the width of the pontoon,and decreases with the increase of the vertical plate height.At the same time,the mooring force increased by 28% near the natural period,in the design of floating breakwater,the corresponding period should be avoided as much as possible.(6)The surge motion of the floating breakwater with vertical plates increases relative to the increase in the height of the vertical plates,but when the relative vertical plate height is S/h=0.27,the pitch of the floating breakwater is reduced by 35% compared to the case of no vertical plates.It can be seen that the increase of the vertical plate can improve the pitch stability of the breakwater.