EFFICIENCY OF VERTICAL SUSPENDED BREAKWATER SUPPORTED ON PILES

El-sadek M. Heikal, Ayman S. Koraim, Ibrahim A. Elbagory

Abstract


The hydrodynamic efficiency of a proposed type of breakwaters was studied using numerical and physical models. The breakwater consists of caisson supported on a pile system and thin plates suspended on the piles under the caisson. A Flow-3D software which is based on the finite differences and volumes was used to examine the hydrodynamic efficiency of the suggested breakwater system. The efficiency of the breakwater was presented as a function of wave transmission, reflection and energy dissipation coefficients. Regular waves with different wave heights and periods and constant water depth were investigated. In addition, different characteristics of the caisson structure, the plates and the pile system were tested. It was found that the transmission coefficient (kt) decreases with the relative caisson draft (D1/h), the relative plate depths (D2/h and D3/h), the relative breakwater width (B/h), and the distance between piles (S) and piles diameters (d) and with decreasing the pile gap-diameter ratio (G/d).Also the reflection coefficient(kr) and the energy dissipation coefficient (kL) increases with the relative caisson draft (D1/h), the relative plate depths (D2/h and D3/h), the relative breakwater width (B/h), the distance between piles (S) and the pile diameter (d) and with decrease of the pile gap-diameter ratio (G/d). The study shows that we can get (kt) values less than 0.25 when D1/h≥0.5, and also when D2/h,D3/h≥0.4at D1/h=0.1. The reflection coefficient (kr) values were between 15 to 55 % for all studied models. The proposed breakwater dissipates about 10 to 30 % of the incident wave energy. In addition, the study shows that the proposed breakwater model has about 75 % efficiency compared with other suspended floating breakwaters.

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