Perforated Wall Breakwater with Internal Horizontal Plate

The hydrodynamic performance of a perforated wall breakwater with an internal horizontal plate is studied. It is suggested that a horizontally submerged plate be installed inside the wave chamber to enhance the stability of the structure. Based on the linear wave theory, the 2D problem is formulated to analyze the wave reflection with different porosity, physical dimensions, and wave conditions. The method of matched eigenfunction expansions is used to obtain the solution. Generally, the hydrodynamic performance of a wave chamber is similar with or without an internal horizontal plate. However, the minimum reflection occurs at some particular ratios of the length of the wave chamber to the wavelength, which are less than the corresponding ratios for a wave chamber without the plate, because the waves become shorter over the submerged plate. Thus, the size of the wave chamber can be reduced. It is also found that a moderate porosity is optimal to dissipate the wave energy. By investigating the wave-induced force and moment, such breakwaters with an internal horizontal plate can be designed and constructed with a higher degree of confidence and reliability.