Experimental Investigation on Wave Reflection Characteristics of Slotted Vertical Barriers with an Impermeable Back Wall in Random Wave Fields

Abstract

Experimental investigations were carried out to assess the wave reflection characteristics of slotted vertical barriers with an impermeable rear wall. This study was carried out to investigate whether these barriers can be used instead of sloped rubble mounds, which occupy a significant area in ports/harbors/marinas, for wave energy dissipation. Thirty-seven different wave barriers (1 vertical wall, 6 different sloped breakwaters, and 30 slotted vertical barriers with porosity in the range of 10–50% and 1–6 slotted barriers) were tested in random wave fields of the JONSWAP spectra in different combinations of significant wave heights and peak periods. For relatively long waves (water depth/wavelength ratio of d/Lp > 0.2), the performances of many combinations of slotted vertical barriers were much better than those of the conventional sloped rubble-mound breakwaters. The results of this study show that by increasing the number of porous walls from one to six, it is possible to reduce the value of the reflection coefficient from 0.9 to 0.3, especially for a d/Lp greater than 0.2. Also, the results show that for a d/Lp less than 0.2, increasing the number of porous walls did not significantly reduce wave reflection. Overall, these results suggest that slotted barriers can be a good alternative to sloped rubble breakwaters for ports, harbors, and marinas, especially in places where good-quality stones are expensive. In addition, this solution helps increase the effective use of space inside the harbor better than do sloped rubble-mound structures.