| In port and coastal engineering,breakwater is an important protective structure.Floating breakwater is usually composed of wave-absorbing floating body and anchorage system,which has certain wave-absorbing ability.Compared with traditional fixed breakwater,it has low cost,convenient construction and does not affect water and sediment exchange.Therefore,it has great application prospects in practical engineering.Based on the open source computational fluid dynamics software OpenFOAM,the RANS equation,SST k-ω turbulence model and VOF method are used to calculate the gas-liquid two-phase flow.The velocity inlet wave generation and the sponge layer boundaries are used to realize the non-reflection wave,thus the three dimentional numerical wave flume is established.Furthermore,the secondary development of OpenFOAM is carried out.The overset grid technology is used to realize fluid-structure interactions when the structure has the larger motion.At the same time,the MOODY program library is transplanted and applied to solve the six-degree-of-freedom motion and mooring force of the floating body,and the numerical model for the hydrodynamic characteristics of the floating breakwater is established.The main contents and conclusions of the paper are as follows:(1)Vertical and oblique inflow of wedge is simulated by overset mesh method.The numerical pressure distributions under different conditions are compared,and the influence of horizontal velocity on pressure distribution is analyzed.The simulation results are in good agreement with the theoretical solutions or simulation values,which shows that the model can reasonably simulate the fluid-solid interaction between the wedge and water.(2)A two-dimensional numerical model of floating body motion is established to simulate the hydrodynamic characteristics of single-box floating breakwater with anchor chain under four periodic waves.Throught the comparing of transmission coefficient,mooring force and anchor chain tension under different conditions,it shows the simulation results are in good agreement with the experimental values,and the error is less than 10%.It means the model can reasonably simulate the interaction between floating breakwater and wave.(3)Based on the numerical model of three-dimensional floating body and wave interaction,the motion of three-dimensional floating breakwater in waves is simulated,and the characteristics of motion response,anchor chain tension and wave surface height are analyzed.It is clarified that the model can be used to simulate the actual three-dimensional floating body motion and provide technical support for the design of floating body motion. |
