Author(s): Michalis Chondros; Vasiliki Katsardi; Vasiliki Tsoukala; Kostas Belibassakis
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Keywords: Flushing Culverts; 3D Numerical Modeling; 3D Wave Diffraction; 3D physical model
Abstract: Numerical modeling of the local 3D wave flow problem at the openings of coastal structures, such as flushing culverts at breakwaters, that allow the periodic exchange of the harbor basin water leading to an improvement of the water quality, has not been studied adequately yet. These openings involve additionally sudden changes in water depth occurring when the incident waves meet the flushing culverts and transmitted into the harbor. A new coupledmode model, based on Eigen functions expansions of the Laplace equation, has been developed and applied to the numerical simulation of such a wave field. The behavior of the numerical solution is examined showing that it converges rapidly, permitting the truncation of the series keeping only its first terms. In order to illustrate the usefulness and applicability of the above method, a new physical model was constructed and experimental measurements were undertaken in the Laboratory of Harbor Works of NTUA. The problem involves measuring time series of surface elevation of regular incident waves to a semi-infinite breakwater that includes a flushing culvert. The wave conditions vary in frequency and amplitude and the culvert dimensions vary both in width and height. In the experimental work, the wave transformations during wave propagation through flushing culverts have shown that the phenomenon is dominated by 3D diffraction effects due to sudden changes in water depth, in conjunction with the finite width of the culvert. Comparisons with the numerical model are presented indicating its ability to simulate 3D diffraction effects, as well as wave transmission through the opening monitored in the experiments.
Year: 2014