Author(s): Kiran G. Shirlal; Subba Rao; Roobin V. Varghese
Linked Author(s):
Keywords: Combined plate breakwater; Inclined plate; Horizontal plate; Test parameters; Wave breaking; Wave transmission
Abstract: Conventional submerged breakwaters in a moderate tidal environment, provide partial protection from waves. They are generally designed for a transmission coefficient of about 0.6 to be effective. In addition to the advantages of submerged breakwater like top freeboard for exchange of surface water, inducement for wave breaking and dissipation of wave energy, the plate breakwater with top and bottom clearance exhibits little interference with currents and sediment transport while saving construction material and hence, is economical and eco-friendly. This paper explains the experiment to evaluate K t of a submerged breakwater with two smooth 0.003m thick plates, one with a horizontal plate of length of 0.50m and another 60 0 inclined plate on the leeside placed at relative depth of submergence of 0.0 and 0.1 at a horizontal spacing varying from 0.05m to 0.20m between the plates. The inclined plate is 0.24,0. 32 and 0.4m long in different water depths so that a clearance of 10% and 21% of the total depth is provided at the top and bottom respectively. The model study was conducted in a the two-dimensional wave flume, 50m long, 0.71m wide and 1.1m deep generating monochromatic waves. The model is tested for wave height varying from0.0. 5 to 0.15m d in water depth of 0.3 to 0.5m while wave period is varied from 1.0 to 2.2 sec. The spacing between the plates acts as an energy damping zone where the wave energy transmitted over the front plate may get dissipated due to turbulence. It is also expected that higher turbulence will be produced as the inclined plate directs the wave upward and interact with the upper layers of the water column. This study demonstrated that, the combined plate submerged breakwater is effective with K t ≤0.6 for almost the whole range of test parameters.
Year: 2010