ON THE EFFECTIVENESS OF OSCILLATING WATER COLUMN DEVICES IN REDUCING THE AGITATION IN FRONT OF VERTICAL WALLS HARBOR STRUCTURES

Abstract

Wave reflection at harbor structures negatively affects the navigability of entrance canals and harbor tranquility. In case of rubble-mound structures this phenomenon is relatively limited if compared to vertical-wall structures. However, in case of deep waters, the use of the latter is an obliged choice due to economic reasons. Furthermore, vertical wall structures are also the preferred choice of harbor managers since they permit a better design of the berthing structures and help the effective use of space inside the harbor. Reducing the wave reflection at vertical wall structures is thus an important measure. To date, several approaches have been presented in the literature (see for instance Huang et al., 2011, and references therein). The effectiveness of slotted vertical perforated-walls has been studied since many years (most recently: Neelamani et al., 2017). Such kind of structure is often also adopted as frontal and internal wall of caisson breakwaters embodying one or multiple chambers (most recently: Ciocan et al., 2017). Another alternative, so far proposed, are caissons with internal rubble mound (Altomare, C., & Gironella, X., 2014). The so called Oscillating Water Column (OWC) concept, commonly investigated as wave energy converter (Falcão, 2010), can also represent a viable alternative to absorb the incident energy thus decreasing its reflection. However, the studies that investigate its effectiveness as anti-reflection device are quite limited (Liu and Geng, 2012, He and Huang 2016). This work aims to contribute to the present knowledge on the effectiveness of an OWC, embodied in quay walls or harbor breakwaters, as an alternative to reduce the wave reflection at vertical wall structures.