Hydrodynamic Analysis Of Multi-row Floating Breakwater

Bottom-fixed breakwater's performance is excellent in terms of wave attenuation.The cost of traditional breakwater increases rapidly with water depth.But the most important is that floating breakwaters have low effect on ocean environment because it does not change current characteristics and can effectively reduce sediment deposition.Specially,box-type breakwater has the advantages of simple structure,light weight,low cost.Floating breakwater has a good performance on wave attenuation in harbor,but it is difficult for wave attenuation of single breakwater to meet the actual requirement.It is necessary to increase the breakwater.Its different form and relative position affect wave attenuation.This paper conducted test to reseach the hydrodynamic and wave attenuation performance of multi-row floating breakwater system.The main contents of this paper are as follows:1.This paper establishes two-dimensional numerical water tank based on viscous theory and compiles the makewave program through UDF(self-defined function)of FLUENT.Sponge layer damping is established to eliminate wave reflection at the end of the tank.VOF is used to capture free surface fluid changes.In order to simulate the interaction between the fluid and the floating breakwater,quadrilateral structure grid is used to disperse the entire water tank,which reduces the CPU and memory consumption of the computer and increases the quality of the grid.Three different meshing schemes are also calculated to determine the optimal form.2.This paper conducted a test to research the floating breakwater.The parameters of the model and layout of the measuring instruments were introduced.The incident and transmitted wave,the tensions in the mooring lines and the motion responses of floating breakwaters were measured.The recorded data were processed to obtain the response amplitude,the maximum tension of the mooring line and the transmission coefficient.3.In this paper,we use the block-coupled meshing technique to realize the mutual coupling motion of the floating breakwaters in sway,heave and pitch by the structural grid in the two-dimensional water tank.Through the numerical simulation and experiment,the wave attenuation characteristics of a single breakwater and multiple breakwaters are analyzed.4.Through data induction and analysis,the effects of different regular wave period and wave height on wave attenuation,motion response and mooring force of single floating breakwaters and multi-row breakwaters were studied.The results show that the variation of regular wave period has obvious effect on the wave attenuation of single and multi-row floating breakwaters.But the influence of wave height is not obvious.The spacing between multi-row breakwaters has little effect on the wave attenuation effect.Wave period and height changes greatly the movement of the breakwater and mooring force.