This study presents a dual-functional system, which is a submerged fluid-filled semi-circular piezoelectric membrane for breakwater and wave energy converter. The mixed Eulerian-Lagrangian method is used to simulate the fully nonlinear waves, deformation of the membrane and variation of voltage on the load . The simulation found that the variation frequency of the strain in the piezoelectric membrane is 2 times of the wave. There exists an optimum resistance of the load that can give the maximum electrical output power. The maximum electrical output power of the piezoelectric membrane occurs as the transmission coefficient of the wave approaches its minimum value.
The utilization of wave energy has been studied by many scholars for several decades. Most of studies focused on the wave energy converter (WEC) with higher wave energy extraction efficiency. This study presents a submerged fluid-filled piezoelectric membrane WEC , which is called SFPMWEC in the following section. Compared with traditional WECs, the wave energy extraction efficiency of SFPMWEC is lower. However, the construction cost of SFPMWEC is much lower than traditional WECs. Other advantages of SFPMWEC are easier maintenance and deployment, non-intrusion and cost sharing with breakwaters. As breakwaters, a submerged fluid-filled flexible membrane has been studied by some scholars. Ohyama et al (1989) had done experiments to study transmission and reflection waves over a submerged bottom-mounted fluid-filled membrane . Phadke and Cheung (1999,2001) studied the response of fluid-filled membrane in linear gravity waves by boundary element method (BEM) coupled with finite element method (FEM). The geometric nonlinearity due to the larger deformation of the membrane is considered in the work of Phadke and Cheung (2003). Das (2009) assumed small amplitude of surface waves and membrane deflection and used the threedimensional, coupled boundary element and finite element model to study the response of a bottom mounted fluid-filled membrane in a wave flume. Liu and Huang (2019) used the mixed EulerianLagrangian method to simulate the fully nonlinear interaction of waves and the submerged fluid-filled flexible membrane. These studies show that the submerged fluid-filled flexible membrane breakwater can reduce the transmission waves greatly at resonance of the membrane system. The resonance of the membrane system means that the maximum response of the membrane occurs as the natural frequency of the membrane system equal to the frequency of the incident wave. Therefore, it is possible to use a submerged fluid-filled piezoelectric membrane as both breakwater and WEC.