The present paper deals with the efficiency of floating breakwaters consisting of an array of truncated vertical cylinders, which can be used to protect nearshore or offshore cites. Extensive experimental data for several configurations of multiple truncated cylinders placed in a wave flume and exposed to the action of both regular and random waves are presented. The transmitted wave field and the exciting forces on particular members of the cylinder array are measured and comparisons are made with corresponding numerical predictions. In addition, first- and mean second - order forces for a number of prototype configurations in the open sea are also given.
In deep waters, where the construction of a conventional breakwater is either impossible or very expensive, floating breakwaters provide an efficient alternative solution to the problem of the protection of nearshore or offshore cites. The present paper deals with the efficiency of floating breakwaters consisting of an array of truncated vertical cylinders. A set of different configurations of cylinders have been experimentally investigated in a systematic way, 1: 10 scaled models of vertical truncated cylinders have been placed in the wave flume of the Laboratory for Ship and Marine Hydrodynamics of the National Technical University of Athens and exposed to the action of both regular waves and irregular seas. Numerical and experimental aspects of the problem are considered. In the numerical study, first- and mean second-order loads on several prototype configurations of multiple truncated vertical cylinders in the open sea are given. The prediction of the mean wave loads on the cylinders is a prerequisite for the design of proper mooring arrangement for the floating breakwater. The first-order diffraction and radiation problems are solved using an exact formulation which makes use of single body hydrodynamic characteristics and takes into account the interaction phenomena through the physical idea of multiple scattering (Mavrakos and Koumoutsakos, 1987; Mavrakos, 1991).
