Ocean surface waves propagating over a spatial arrangement of subsurface fixed horizontal plate breakwaters crowned with flexible medium

Abstract This paper presents an arrangement of sub-surface fixed horizontal plates as an alternative to single long plates and conventional breakwaters. Through experimental tests in a wave flume, their capability as coastal protection elements was evaluated varying the number of plates and their spacing, as well as the roughness of their crowns by means of three different flexible covers. Due to the spatial arrangements, a Bragg reflection was achieved but it did not improve the plate performance. The results suggest that the plates work best when their spacing is far from this resonance condition. In general, the minimum spacing is recommended for maximizing wave energy dissipation. Wave transmission had lower values when increasing the number of plates. Energy redistribution was observed from low to high frequencies of the spectra due to non-linear interactions. Wave skewness was calculated but remained low in the sheltered area. Moreover, the flexible cover was useful for filtering the waves in the frequency range between 1.5 and 3.5 times the peak frequency of the spectrum, with a more complex role in the dissipation of energy of longer waves.