ABSTRACT

In this paper, the hydrodynamic performance of floating breakwaters in reducing wave transmission is investigated experimentally. The action of 2D regular waves is considered. Emphasis is given on the effect of the incident wave characteristics, the draft and the filler in the floating box. Comparison of the new structure is also made to the previous studies. The experimental results show that the wave transmission coefficient is generally reduced with increasing value of B/L. The incident wave period rather than the wave height is the main factor on reducing the transmitted wave energy. The draft of the floating body do affects the effectiveness of breakwater. The transmitted coefficient decreases with increasing draft. When the floating box is ballasted with water, there exists in the inside of the floating breakwater a resisting force against the wave force outside. This resisting force significantly improves the effectiveness of the breakwater. Compared to previous well-known model, the anti-rolling type floating breakwater in this paper has competitive effectiveness in reducing the transmitted waves.

INTRODUCTION

Floating breakwaters have been increasingly and extensively used as alternative structures in port or coastal protection, which display natural advantage in terms of construction, economics and ecology compared with permanently fixed breakwaters. They are especially competitive for coastal areas with a high tidal range or deep water depth.

In the past three decades, various floating breakwater structures have been proposed, such as the Cage-type breakwater (Murali and Mani, 1997), the spar buoy floating breakwater fences (Liang et al., 2004), the π shaped floating breakwater with two additional side-boards (Gesraha, 2006), the thin plane board floating breakwater with rows of net underneath (Dong et al., 2008), the horizontally interlaced floating pipe breakwater with multi-layers (Hegde et al., 2008), the diamond-shape blocks assembled porous floating breakwater (Wang and Sun, 2010), the floating breakwater with truss structures (Uzaki et al., 2011), the rectangular floating breakwater with pneumatic chambers (He et al., 2012, 2013), the floating breakwater with slotted barriers (Huang et al., 2014), the floating breakwaters with double-layered perforated walls (Xiao et al, 2015), the cylindrical floating breakwater (Ji, 2016), and the WEC-type floating breakwater (Ning, et al 2016). However, an important problem these structures present is the limited range of wave heights and periods for which they are really effective. Furthermore, the effectiveness of wave energy attenuation is limited by the used materials. As the traditional material, steel or reinforced concrete structure must contend with the fact that the former is highly corrosive under the salt seawater environment and the latter is fragile in dynamic loading.

This content is only available via PDF.
You can access this article if you purchase or spend a download.