Comparison of hydrodynamic performance of floating breakwater with taut, slack, and hybrid mooring systems: An SPH-based preliminary investigation

Abstract

A tautly moored floating breakwater exhibits favorable wave attenuation performance at a specific sea level, and a slackly moored floating breakwater is more adaptable to tidal variation. To bring their merits into full play, a hybrid mooring system composed of seaward taut ropes and leeward slack chains is proposed. Then, a Smoothed Particle Hydrodynamics-based numerical model is built to compare the wave transmission and reflection coefficients, mooring forces, and motion response of a floating breakwater with taut, slack, and hybrid mooring systems, respectively. The results show that, at low tide, a tautly moored floating breakwater has the best wave attenuation performance. A hybridly moored floating breakwater comes second, but its mooring forces are smaller. At high tide, in the shorter-wave regime, the taut mooring system still leads to the best wave attenuation performance, while in the longer-wave regime, a hybrid mooring system becomes the best. Notwithstanding the respective dominant regimes of the taut and hybrid mooring systems at high tide, the hybrid mooring system is always subjected to smaller mooring forces. It is hoped that this applied research can shed light on the engineering design of the mooring system of the floating breakwater.