American Society of Civil Engineers


Hydrodynamic Efficiency of a New Design of Half-Submerged Breakwater Compared to a Rectangular Caisson


by G. Duclos, (Laboratoire de Mécanique des Fluides, CNRS UMR6598, Ecole Centrale de Nantes, 1 Ruc de la Noe, Nantes 44300, France), C. Josset, (Laboratoire de Mécanique des Fluides, CNRS UMR6598, Ecole Centrale de Nantes, Nantes 44300, France), A. H. Clément, (corresponding author), (Laboratoire de Mécanique des FLuides, CNRS UMR6598, Ecole Centrale de Nantes, Nantes 44300, France E-mail: alain.clement@ec-nantes.fr), L. Gentaz, (Laboratoire de Mécanique des Fluides, CNRS UMR6598, Ecole Centrale de Nantes, Nantes 44300, France), and C. Colmard, (SAIPEM, Saint Quentin en Yvelines, France)

Journal of Waterway, Port, Coastal and Ocean Engineering, Vol. 130, No. 3, May/June 2004, pp. 127-133, (doi:  http://dx.doi.org/10.1061/(ASCE)0733-950X(2004)130:3(127))

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Document type: Journal Paper
Abstract: In this paper, the wave transmission, reflection, and energy dissipation characteristics as well as the hydrodynamic forces of two partially submerged breakwaters are compared. The breakwaters under consideration are designed to be installed in coastal areas where the water depth may be important (typically 50 m), making traditional bottom seated configurations unsuitable. They are composed of a free-surface piercing caisson mounted on vertical piles. The first breakwater considered in this study, as a matter of reference for comparison, is a rectangular caisson. The second one is a new profile proposed by Colmard and called BYBOP by the writer. The seaside face, fronting the ocean, is an elliptic profile while the harbor side is a plane inclined 55° to the vertical. A numerical simulation on both these shapes, at model scale, was carried out in two numerical wave tanks. The first one, CANAL, is based on fully nonlinear potential flow theory while the second one, ICARE, is a Reynolds averaged Navier.Stokes equations solver simulating viscous free-surface flow around structures. The problem is considered as a two dimensional one and solved in the time domain. Reflection, transmission, and dissipation coefficients are computed, together with hydrodynamic forces, on the two different caisson shapes. The new design is shown to have far better efficiency, at less material expenses, for the same width.


ASCE Subject Headings:
Hydrodynamics
Breakwaters
Caissons
Waterfront structures
Wave reflection
Numerical models