Numerical Simulation of Solitary Wave Power Absorption by Rotating Slotted Flappers using Incompressible SPH Method

Abstract

Abstract In this study, the incompressible smoothed particle hydrodynamics (ISPH) as a mature enough mesh-less method is applied to simulate the oscillatory motion of different slotted rotating flappers at the end of a numerical tank under the hydrodynamic load of a solitary wave. The solitary wave can be considered a simple model of ocean waves with long-lasting source of eco-friendly and renewable energy. Many engineering devices such as rotating flappers have been proposed and designed to capture this energy. On the other hand, these structures can also be applied to withstand destructive waves for example Tsunami waves with huge potential to cause severe damage to coastal structures and loss of life in shore regions. This study investigates the performance of a number of 2-D rotating bottom-hinged flappers slotted with different patterns representing a new conceptual model of a wave energy absorber device capable of protecting coastal structures. With providing structural facilities, various slotting patterns can be arranged for a single flapper to have appropriate performance for different wave conditions with the lowest construction cost. Based on the obtained numerical results, it has been found that the spring stiffness of the flapper has the most important physical parameter determining the amount of wave power extraction. In addition to this, the spring friction also has a significant effect on the dissipation of the absorbed power. The slotted flappers also show different rotational motion with less captured power in comparison with the solid flapper. Several physical properties such as the slotted area provided in the flapper and the corresponding pattern, the spring stiffness and friction and other related properties must be determined to protect desired structures at the predefined level and capture maximum energy as much as possible. The findings of this research can be used as a preliminary guide to design more realistic 3-D protective flappers for complex flow conditions.