Background The floating breakwater has been favored by experts and scholars at home and abroad due to its advantages such as good wave dissipation, lightweight, economy and environmental protection, etc. Prior to this study, our research team successfully implemented a high-density polyethylene (HDPE) floating raft-type breakwater in Fujian's marine environment, confirming its capacity to effectively attenuate wave energy within a defined zone. The results of field test showed that its wave dissipation efficiency reached −33.33% to −42.86%.
Objective This study aims to further optimize the wave dissipation performance of the HDPE floating raft-type breakwater and provide scientific experimental basis.
Methods The paper conducted tank simulation experiments on the damping net of HDPE floating raft-type breakwater, and studied the wave dissipation effect of the damping net by analyzing the influence of various factors mesh size (2a), net spacing (D), number of nets (N), and draft depth of nets (d) on the wave height and wave energy.
Results The experimental results showed that the mesh size, net spacing, number of nets, and draft depth of nets of the damping net all affected their wave dissipation effect. 1) The wave dissipation effect of the nets increased with the decrease of the mesh size and the increase of the number of nets. 2) Under the experimental wave condition of wave height (H) 6 cm wave steepness ( \dfracHL ) =0.038, L was the wave length, the net spacing arranged at 115.0 cm had better wave dissipation effect than those at 1.5 cm. Under the experimental wave condition of wave height 10 cm ( \dfracHL =0.045), the mesh size and the number of nets had crucial impact on the wave dissipation effect of nets.When the mesh size was 1 mm and number of nets were more than 4, the net spacing arranged at 1.5 cm had better wave dissipation effect than those at 115.0 cm. When the mesh size was 4 mm, the net spacing arranged at 1.5 cm also had better wave dissipation effect than those at 115.0 cm. 3) Under the wave conditions of wave height 6 cm ( \dfracHL =0.038) and 10 cm ( \dfracHL =0.045), the larger the draft depth of nets, the better the wave dissipation effect. However, when the ratio ( \dfracdh ) of the draft depth of nets to the water depth of tank (h) reached 0.2, the influence of that on the wave dissipation effect became moderate. When the draft depth of nets was smaller, the nets performed better in the wave dissipation effect under the wave condition of wave height 6 cm ( \dfracHL =0.038). When the draft depth of nets was more than 64 cm and \dfracdh approached 1.0, the nets performed better in the wave dissipation effect under the wave condition of wave height 10 cm ( \dfracHL =0.045).
Conclusion Therefore, while ensuring structural strength, we can optimize the nets configuration by considering parameters like mesh size, net spacing, number of nets, and draft depth of nets, combined with the wave characteristics of the target sea area. This approach balances wave dissipation performance and cost, fully leveraging the wave dissipation potential of nets.
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