"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:5e91b150-3d62-462e-83f0-0efe570df822","http://resolver.tudelft.nl/uuid:5e91b150-3d62-462e-83f0-0efe570df822","Spatial distribution of wave overtopping","Van Kester, D.C.P.","Verhagen, H.J. (mentor); Uijttewaal, W. (mentor); Smith, G. (mentor); Stive, M.J.F. (mentor)","2009","The goal of this master thesis is to describe the spatial distribution of the wave overtopping discharge over and behind the crest of a coastal defence structure. The influence of the most relevant parameters on this process is explored. This research has been performed by means of a physical model. The following relevant parameters were varied during the experiments to consider their influence on the spatial distribution of the wave overtopping discharge: wave height, wave steepness, water depth, crest height and wave spectrum. Four different types of wave overtopping discharges were measured in this research: total wave overtopping discharge, wave overtopping discharge directly behind the crest, wave overtopping discharge over impermeable backfill and wave overtopping discharge over permeable backfill. Based on the equality of the comparison between the experiment results and existing theoretical methods to calculate the total wave overtopping; further experiment results are considered as acceptable and reliable and can be used to derive the relation for the spatial distribution of the wave overtopping discharge. The total overtopping discharge flows over the crest of the breakwater and is divided in two components: the infiltrated discharge into the crest and the overtopping discharge directly behind the crest. A method to describe this distribution is defined. This method includes the influence of the wave height, wave length and crest height. The spatial distribution of the wave overtopping discharge behind the crest depends on the permeability of the backfill. For an impermeable backfill with a slope of 3% towards the breakwater, the overtopping discharge at every point behind the breakwater is divided in two parts: one part flows back over the impermeable backfill under the influence of gravity and the other part passes the point and travels further away from the breakwater. The final relation between the reduction factor (ratio between the overtopping discharge at a certain distance behind the crest and the overtopping discharge directly behind the crest) and the distance behind the crest was found to depend on a dimensionless presentation of the wave energy flux. For a permeable backfill, the overtopping discharge at every point behind the breakwater is divided in two parts: one part infiltrates into the backfill and the other part passes the point and travels further away from the breakwater. The influence of the wave energy flux on the relation between the reduction factor and the distance behind the crest was found to be smaller than for an impermeable backfill.","spatial; distribution; wave; overtopping; backfill; crest; wave; energy","en","master thesis","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c329464e-0911-4b30-9a87-94470f298f9c","http://resolver.tudelft.nl/uuid:c329464e-0911-4b30-9a87-94470f298f9c","Generating electricity from waves at a breakwater in a moderate wave climate","Schoolderman, J.E.","Molenaar, W.F. (mentor); Zijlema, M. (mentor); Reedijk, B. (mentor); ten Oever, E. (mentor); Vrijling, J.K. (mentor)","2009","The purpose of this thesis was to develop a preliminary concept design of a wave energy converter. The type of device designed was limited by several starting points which stipulated, among other criteria, a robust structure which can be constructed within a breakwater and can generate electricity from a fairly mild (in the order of Hs=0.5-1.5m) and regularly occurring wave climate. Integration with a caisson breakwater was selected to ensure survivability. Three concepts using the theories of wave overtopping, wave run-up, and wave pressure were evaluated. A multi-criteria analysis was performed on the three concepts. Concepts were scored based on power output, functionality in wide range of conditions, ease of construction, and theory reliability. Theory reliability was scored based on the three aforementioned criteria. The concept analysis concluded the most promising device to further investigate was the concept based on the theory of wave pressure. This device excelled in (theoretical) output having the highest peak power and wider power curves. In the concept, wave pressure is exerted on an underwater opening. This opening leads water into a pipe with a gradual constriction. This constriction increases the pressure allowing the water to be brought to an optimal level above MWL. Through a turbine the water is returned to MWL. A model was built with three different opening ratios and three separate basins open to the wave flume at the bottom. A series of tests were performed of varying wave climates and crest freeboards. During the tests the head difference was measured between the internal basins and the water elevation at the rear of the model. The holes in the bottom of the basins allowed for constant flow of water out of the basins and a calculation of flow rate based on the hydraulic head was required. This allowed for the calculation of the theoretical power generated during the tests. Additionally, the input wave power was known so the device efficiency could be calculated for each test allowing for the identification of the optimal geometry and the generation of a full-scale efficiency curve. The device was evaluated at two design locations in Panama and Japan. The wave climate, tidal influence, system headloss, and sea level rise were calculated in order to discover the power generation at each location. Revenue associated with the generation of electricity was calculated to give an indication of the device’s cost effectiveness. It was found that sea level rise has a negligible impact on efficiency if sea level rise is appropriately accounted for. The impact is in the order of 1.5% over 50 years if the rise is assumed to be 80cm over 100 years. Including sea level rise, the device has been calculated to generate an average of 16,413 and 5,766 kWh/m/yr at Panama and Japan, respectively. The report concludes that the proposed design can be constructed using existing techniques for caisson construction. However, the design must be further optimised and tested in order to become a fully feasible wave energy converter.","wave; energy; converter; caisson; breakwater; pressure; wave energy converter; wave pressure; renewable energy","en","master thesis","","","","","","","","2009-09-27","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""