Numerical simulation of the wave dissipation performance of floating box-type breakwaters under long-period waves

Floating breakwaters tend to be ineffective under the effect of long-period waves, and thus, research on their wave dissipation performance is crucial for harbour engineering structures. Based on the open-source OpenFOAM software, a numerical model for the interactions between waves and floating breakwaters is established. Floating breakwaters are transplanted into the wave flume by the overset grid method. The MooDy program library is applied to simulate the mooring system. The effects of the wave period, relative draft depth, number of floating breakwaters, distance between floating breakwaters, rigidity of mooring lines and length of floating breakwaters on the wave attenuation performance of floating breakwaters are studied. It is concluded that the most suitable relative draft for containers as floating breakwaters is 75%. The most suitable floating breakwaters' spacing is 0.3L (L is the wave length) to 0.12 L as the wave period increases from 8 to 14 s. The stiffness of the mooring line and length of the floating breakwater are the most direct ways to improve the wave dissipation performance. Using four containers to form two breakwaters instead of a long breakwater can improve the functionality of the mooring line and the wave dissipation capacity.