The Focusing Waves Induced by Bragg Resonance with V-Shaped Undulating Bottom

Abstract

Intensive wave reflection occurs when the wavelengths of the incident waves and bottom undulations are in a 2:1 ratio. Existing studies have included the Bragg resonance phenomenon of waves passing over a continuous undulating bottom parallel to and oblique to the shoreline. More generally, the Bragg resonance mechanism is used as a means of coastal protection, rather than wave power generation. To focus the wave energy in a specific area, here, we propose sinusoidal sandbars of a horizontal V-shaped pattern, which is formed by two continuous undulating bottoms inclined at an angle to each other and the center axis of the angle is perpendicular to the shoreline. Based on the high-order spectral (HOS) numerical model, both the characteristics of Bragg resonance induced by the regular waves and random waves are investigated. In the scenario of regular waves, it shows that the wave-focusing effect is related to the angle of the V-shaped undulating bottom, and the optimal angle of inclination for the V-shaped undulating bottom is 162.24°. On that basis, considering the interactions between the random waves and the V-shaped undulating bottom of 162.24°, the Bragg resonance characteristics of random waves are studied. The BFI factor combining wave steepness and spectrum width can evaluate the focusing intensity of the Bragg resonance of the random waves. For BFI, in the range of 0.15–1.0, the values of Hsmax/Hs0 linearly increase with the increase of BFI.

Storm Tide and Wave Simulations and Assessment II

“…To evaluate the focusing waves induced by Bragg resonance with a V-shaped undulating bottom, Zhang et al [3] proposed sinusoidal sandbars with a horizontal V-shaped pattern that was formed by two continuous undulating bottoms that were inclined towards each other at an angle with the center axis perpendicular to the shoreline. Based on the high-order spectral (HOS) numerical model, both the Bragg resonance characteristics that were induced by the regular waves and random waves were investigated.…”

Directing Shallow-Water Waves Using Fixed Varying Bathymetry Designed by Recurrent Neural Networks

“…Deng et al [28] demonstrated that an oscillating water column converter installed over a submerged breakwater with a proper configuration can have significantly higher energy absorption efficiency compared to a flat seafloor. Zhang et al [29] developed a V-shape undulating bottom that enables wave focusing for energy harvesting. However, it is not trivial to design a bathymetry that directs shallow-water waves to a target location, and to the best of the authors' knowledge, there is no existing tool available for this task.…”

Numerical and Experimental Study on the Bragg Reflection of Water Waves by Multiple Vertical Thin Plates

“…Apart from the sinusoidal or cosinoidal seabed topography, the Bragg reflection of water waves induced by artificial structures on the seabed has also been widely investigated. These artificial structures can be formed into various shapes, such as rectangular shape [8,9], trapezoidal shape [10,11], trench [12,13], semi-circular shape [14,15], parabolic shape [16,17], triangular shape [18] and V-shape undulating bottom [19].…”