Scattering of Surface Gravity Waves by a Pair of Floating Porous Boxes

Abstract

A numerical model is developed based on multidomain boundary element method (MBEM) to investigate the scattering of surface gravity waves by a pair of floating porous boxes. This study reveals that there is a significant reduction in wave forces acting on the boxes with the introduction of structural porosity. Moderate porosity is highly effective for shallow and intermediate water depth for dissipating wave energy, while high porosity is more suitable in case of deep water. A major part of the wave energy is trapped by the porous boxes when the widths of the boxes are close to half of the wavelength of the incident waves. Apart from wave reflection and energy dissipation, a pair of floating porous boxes traps a part of wave energy, which helps in the wave attenuation on the lee side of the porous box. Horizontal and vertical forces of the seaside porous box are 180 deg out of phase, while they are in-phase in case of the box located on the lee side. Optima in the horizontal and vertical forces are attained when the distance between the boxes are at periodic intervals of half the wavelength. This study will be of immense help in the design of box-type porous structures as effective wave barriers for the creation of tranquility zone in the marine environment.