Numerical Investigation of a Novel Wave Absorbing Method Based on Gap Resonance

A new wave absorbing approach based on the mechanism of gap resonance is proposed in this work. The wave absorber is designed by placing a fixed box in front of the end of a physical wave flume, thereby forming a gap between the box and the end wall. To facilitate matching between the resonant frequency and the incident wave frequency, the gap width, box draft, and box breadth are jointly adjustable. A slatted screen is introduced into the gap to obtain the appropriate damping effect, if necessary. Numerical examinations are conducted to investigate the efficiency and applicability of the proposed resonant wave absorber based on a fully nonlinear finite element numerical wave flume within the modified potential flow theory. The numerical results confirm that the resonant wave absorber can achieve a high efficiency for a wide range of wave frequencies. Small reflection coefficients of K-R < 5% are obtained for all wave conditions examined in this work. Moreover, the size of the wave absorber (measured in the wave propagation direction) is less than 40% of the incident wave length (for example, the wavelength lambda is an element of [1.02 m, 6.55 m] and the water depth h= 0.5 m). The main advantage of the present method is that it can lead to fairly small reflection coefficients for extremely long waves even with relatively small flume sizes, for which the widely used artificial sloping beach generally fails.