Performance of bi-stable PWAs under irregular waves

Because of their wide resonant frequency bandwidth which extends to the lower range of wave frequencies, the research community has recently paid significant attention to the design and performance analysis of bi-stable point wave energy absorbers (PWAs). Along this line, we dedicate this study to shed more light onto the behavior of bi-stable PWAs under random wave excitations. We use Monte Carlo simulations to study the effect of the wave spectral content on the statistical response of the absorber; mainly the average output power and the average capture width ratio (CWR), for different shapes of the potential energy function of the absorber. We show that there is a direct correlation between the stochastic response of the absorber and its steady-state behavior under harmonic wave excitations. In particular, we show that the PWA exhibits its best performance when the peak frequency of the waves’ spectral density function is tuned to the center of the steady-state effective bandwidth of the absorber, where large-amplitude inter-well oscillations of the buoy are uniquely realized. We develop design maps to demonstrate how the CWR of the bi-stable PWA varies with the peak frequency and significant height of the waves. We use those maps to demonstrate how to design the shape of the potential energy function of the absorber to maximize the CWR for waves of known spectral content. We believe that such understanding is vital to design effective bi-stable PWAs.