An experimental study of a rectangular floating breakwater with vertical plates as wave-dissipating components

Abstract

Floating breakwaters have received growing attention in recent years from academic and engineering sectors alike. The wave-dissipating components are commonly attached to the bottom of floating breakwaters for better wave protection performance. Vertical plates, which have been proven effective in dissipating waves, were attached to a rectangular floating breakwater in this study. A series of experiments were conducted under regular wave conditions to analyze the wave protection and motion response performances, and the effects of mounting position, mounting rows, plate porosity, and protruding plate height were examined. Our experimental results elucidated that the pitch motion plays a critical role in dissipating energy. Although variation in the settings, such as mounting with more than one row of plates, smaller plate porosity and longer protruding plate height do not cause significant changes in the mass and moment of inertia of floating breakwater, they all exert stronger confining effects on the water body beneath. The water body confined by plates significantly changes the dynamic characteristics of floating breakwaters, and increase the natural period of pitch motion towards longer waves. As a result, the violent energy dissipation and corresponding better wave protection occur at longer waves. It has been demonstrated that the primary working function of vertical plates as wave-dissipating components is due to water body confinement. This finding can be utilized to tailor the design of the vertical plates as wave-dissipating components in accordance with the seasonal weather and sea conditions at specific engineering sites.