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Please use this identifier to cite or link to this item: http://hdl.handle.net/1860/1465

Title: 2DV hydrodynamics of emerged rubble-mound breakwaters
Authors: Koutandos, Evangelos
Prinos, Panayotis
Koutitas, Christofer
Keywords: Coastal structures;Coastal hydrodynamics
Issue Date: 12-Sep-2006
Publisher: Michael Piasecki and College of Engineering, Drexel University
Citation: Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732
Abstract: In the present study the 2DV hydrodynamic characteristics of emerged rubble-mound breakwaters with or without overtopping is studied numerically using the Cornell Breaking waves and Structure (COBRAS) model, Liu et al. (1999), Liu et al. (2000), Garcia et al. (2004). The COBRAS model solves the 2DV Reynolds Averaged Navier-Stokes (RANS) equations, based on the decomposition of the instantaneous velocity and pressure fields into mean and turbulent quantities. Reynolds stresses are closed with an algebraic non-linear k-ε turbulence model, which can solve anisotropic–eddy-viscocity turbulent flows. The flow in the porous structure is described in the COBRAS model by the Volume-Averaged Reynolds Averaged Navier-Stokes (VARANS) equations, obtained by integration of the RANS equations in a control volume larger than the pore structure but smaller than the characteristic length scale of the flow. Another set of k-ε equations similar to the previous one is used to model turbulence production-dissipation within the porous medium, Hsu et al. (2002). Two characteristic cases are examined numerically: (A) emerged breakwater without overtopping and (B) emerged breakwater with overtopping. In both cases numerical results, concerning the free surface evolution along the wave flume, are compared satisfactorily against experimental results from the European Project Delos. The 2DV hydrodynamic characteristics and the main differences between the two cases examined numerically are revealed concerning the 2DV velocity and turbulence kinetic energy fields before, over and after the structure. It is revealed that overtopping has a crucial affect in the mean field (velocity field), since much higher maximum velocities are observed mainly in the front upper part of the structure in the overtopping case and (B) in the turbulence field (turbulence kinetic energy field) since much higher maximum values are observed not only in the front upper part of the structure in the overtopping case but also in the porous body of the structure. These facts are mainly due to the stronger wave-structure interaction and the more intense momentum exchange through the water-porous material interface in the case of overtopping. Thus it is evident that overtopping can cause severe damages mainly in the front part but also in the core of emerged rubble-mound breakwaters due to the increased turbulence intensity.
Description: Paper presented at The Seventh International Conference on HydroScience and Engineering (ICHE) hosted by the College of Engineering at Drexel Univeristy on September 10-13, 2006 in Philadelphia, Pennsylvania. The conference theme was IT in the Field of HydroSciences. It included several mini-symposia that emphasized IT topics in HydroSciences and the yearly meeting of the metadata group of the International Oceanographic Data and Information Exchange organization.
URI: http://hdl.handle.net/1860/1465
ISBN: 0977447405
Appears in Collections:Proceedings of the 7th International Conference on HydroScience and Engineering (ICHE 2006) [ISBN: 0977447405]

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