Study On Hydrodynamic Performances Of A New Type Of Floating Breakwater For Emergency

A new type of floating breakwater,mounted with wave dissipation units,was presented for the application to emergency aiding and temporary protection.It had the advantages of flexibility,economical efficiency,recyclability,and convenient transportation and installation.Flume experiment was performed to study the effects of wave steepness,relative draft,relative width and chain length on wave dissipation effect of the floating breakwater,and the effects of relative width,relative draft and wave height on mooring forces and motion responses of models.Main foundings are summarized as follows.Single perforated tube with the ratio of chain length over water depth being 2:1has the optimal wave dissipation effect.The transmission coefficient is decreased with wave steepness,relative width and relative depth,while it is increased first and then decreased in the case of deep water and large wave height.This type of floating breakwater has a significant wave dissipation effect when wave height is relatively small.Wave height is the main factor of the motion responses of floating body.Sway,heave and roll increase with wave height.Sway and heave basically decrease with relative width.Roll decreases with relative width for model one and five,while it increases for model two and three.Mooring force decreases with relative width and has a poor correlation with relative draft.FLOW-3D software was used to simulate the movement of the floating breakwater under regular wave.The numerical model was validated by comparing the results of flume experiment.The influence of relative draft on the transmission coefficient and mooring forces were investigated.Numerical results indicate that the transmission coefficient and mooring force decrease with relative draft within a certain range.The wave dissipation effect of this structure is fine,which provides a reference for its application.