Modeling of energy extraction and behavior of a Flexible Floating Breakwater

In the present paper, linear hydroelastic analysis is performed for the assessment of the behavior of a Flexible Floating Breakwater (FFB), which represents not only a structure for shore protection but also a device for wave energy production with the utilization of a linear hydraulic Power Take-Off mechanism (PTO). The linear hydroelastic analysis is conducted in frequency domain with a radiation/diffraction 3D hydrodynamic model considering the effect of the flexibility of the FFB as well as the damping associated with the energy extraction by the PTO mechanism. A framework for this analysis is proposed and demonstrated, which includes three components: (a) a 3D structural model for an initial eigenvalue analysis, (b) a 3D hydrodynamic model for the hydroelastic analysis and (c) a numerical analysis for the calculation of the forces associated with the PTO and, also, for the estimation of the generated power. FFB consists of a grid of flexible floating modules connected flexibly in two directions by: (a) connectors with known properties and (b) hydraulic Power Take-Off mechanisms with known linear damping characteristics. The PTO mechanisms can be oriented in any possible direction in space. The investigation of the FFBs’ behavior is executed for two grids with different number of modules as well as for different combinations of translational and rotational stiffness of the FFB's connectors and different damping coefficients of PTO. The combined effect of wave energy extraction, behavior and a desired level of protection by the FFB is illustrated.

► The proposed numerical framework is general and can be applied in a variety of cases of wave energy converters consist of Power Take-Off (PTO) mechanisms.
► Flexible Floating Breakwaters (FFBs) as oscillating bodies can produce power with the utilization of a linear PTO mechanism.
► Effectiveness for both wave energy production and a desired level of protection by the FFB is illustrated to be possible.
► The wave angle, PTO angle, total number of the FFBs’ modules and rotational stiffness of the FFBs’ connectors affects strongly the produced power and the protection.