Print Email Facebook Twitter Artificial Surf Reefs Title Artificial Surf Reefs Author Henriquez, M. Contributor Battjes, J.A. (mentor) Stive, M.J.F. (mentor) Fontijn, H.L. (mentor) Reniers, A.J.H.M. (mentor) Janssen, T.T. (mentor) Faculty Civil Engineering and Geosciences Date 2005-01 Abstract Artificial Surf Reefs (ASR) are built to improve the surf conditions of the waves. Three ASR have been realized over the last decade and many more are planned to be constructed within a period of ten years. Even though a hot topic, ASR design is often done fairly ad hoc and there remains great uncertainty as to what the optimal dimensions of the ASR should be. Through combination of numerical and experimental modeling efforts, this study aims at: 1) Improving our general understanding of how ASR design affects the actual surfability; 2) Designing an optimal reef shape; 3) Obtaining measurements of the surfability parameters to verify the predicted surfability by the numerical wave model. The quality of a surf break is expressed in four measurable parameters: breaker height, breaker shape, peel angle and the attendant currents. Usually a surf break differs from other places along the coast by the ability to make waves peel along their crest. Therefore the peel angle is studied thoroughly. By considering idealized topographies, the important reef properties that affect the peel angle become clear. The model applied in the numerical study is a state-of-the-art, deterministic amplitude evolution model that takes into account quadratic interactions (triad interactions). Optimal shape dimensions were estimated in the numerical study for varying reef shapes and wave conditions. The resulting ASR design was constructed in a wave basin in the laboratory of Fluid Mechanics of the Faculty of Civil Engineering. Unidirectional incident waves (regular and bichromatic) were generated by three piston type wave makers with second-order wave board control. The laboratory observations were used to verify three parameters that were predicted with the numerical study: breaker height, breaker shape and the peel angle. The combined numerical and experimental study shows that: Two reef properties are needed to obtain surfable peel angles. First there must be a certain angle enclosed between the reef normal and the offshore wave direction. Secondly, the depth at which the reef starts needs to be sufficiently shallow. The reef shape performs optimal when the tip of the reef is relatively sharp. This results in less intense breakers suitable for the take-off. The predicted surfability parameters by the numerical wave model agreed well with the laboratory measurements. The experiment showed that the water depth over the reef crest significantly affects the breaker shape. Also the currents over and around the reef have a significant impact on the surfability of the surf break. To reference this document use: http://resolver.tudelft.nl/uuid:75b15cd7-08a1-48e5-8fc9-337f184ae318 Publisher TU Delft, Faculty of Civil Engineering and Geosciences, Hydraulic Engineering Part of collection Student theses Document type master thesis Rights (c) 2005 M. Henriquez Files PDF 2005Henriquez.pdf 1.99 MB Close viewer /islandora/object/uuid:75b15cd7-08a1-48e5-8fc9-337f184ae318/datastream/OBJ/view