Computational and experimental studies of wave–structure interaction: Wave attenuation by a floating breakwater

Abstract

Interactions between surface gravity waves and a floating rigid body are complex, as waves may reflect from, break on, and be transmitted behind the body. Studies of these phenomena are critically important in improving the safety and functional efficiency of offshore structures. Here, the wave attenuation performance and motions of a type of floating breakwater (FB) are studied through numerical and experimental approaches. A numerical wave tank (NWT) is developed based on the software OpenFOAM and properties of wave channel from a laboratory. In the NWT, the air–water interface is captured by the volume of fluid method. The motions of FB are tracked by the six degrees of freedom model. A mooring system model is developed to simulate the constraints of the FB. Large eddy simulation turbulence modeling is implemented for the wave breaking processes. A model FB with a scale of 1:20 is tested in both the experimental and numerical wave channel. Wave heights at the back/front of the FB and the constraint forces of the mooring wires are measured. The numerical models are validated by comparing the results with experimental measurements. The variations of transmission/reflection coefficients, energy dissipation rate, and maximum mooring force are calculated. Changes of the response amplitude operators with the ratio of FB width to wavelength ([Formula: see text]) and wave steepness are analyzed. The wave transmission coefficient will drop below 0.8 if the value of [Formula: see text] is larger than 0.3, but will go over 0.95 if [Formula: see text] is less than 0.1. Wave steepness has a large influence on FB motions and the mooring system. The effect of Stokes drift is observed by the shift of position of the FB.

Enhancing Hydrodynamic Performance of Floating Breakwaters Using Wing Plates

“…The wave attenuation performance and movement of some types of floating breakwaters (FBs) have been reported by Ning et al [21], who used numerical and experimental approaches to study and develop a mooring system model to simulate FB limitations. The effectiveness of a series of porous breakwaters in reducing wave forces on a floating dock has been studied by Gayathri [22], based on the theory of small-amplitude water waves at finite water depth.…”