AbstractsPhysics

Detrimental impacts of fossil fuels and its foreseen scarcity are encouraging research for the development of the renewable energy as alternatives. A newly developed composite seawall concept could be a vitally important technique for wave energy conversion. A 3-D model of composite seawall has been simulated to comprehend its hydraulic performance. Composite seawall is a dual-purpose overtopping type of coastal shoreline device and wave energy conversion is considered as by-product of the seawall. Overtopped water generates hydraulic head convertible to electricity by means of low head hydro-power generator. A 3-D physical model of composite seawall has been developed and tested for both normal and oblique waves in this study. Fraude scale laws (geometric scale 1:50) are followed in the model scaling. Total 72 simulations are conducted, and overtopping and hydraulic power generated at the crest of the ramp of the composite seawall for each simulated wave parameters are recorded. Hydraulic performances are measured based on the input wave parameters and results. Wave breaker screen is also modeled and tested (by 12 simulations) to measure its suitability as outfall. Results show that maximum achievable hydraulic efficiency of the composite seawall is about 33.6 % and average hydraulic efficiencies are about 26.6%, 18.6%, 15.9% and 11.1% for the freeboard of 0.5 m, 1.0 m, 1.5 m and 2.0 m respectively. Hydraulic performance decreases for oblique wave approaches. Average hydraulic efficiency of a composite seawall (having 1.0 m freeboard) is about 20% in case of 1.0 m tidal variation. Composite seawall is not suitable option for high tidal variations and low wave heights. Wave breaker screen is a suitable outfall option but it decreases hydraulic head generated in the composite sea walls up to 12.5%. Composite sea walls for wave energy extraction could be suitable option in such a remote place such as Islands, where conventional energy supply would be highly expensive and rarely possible.