Author(s): Hideo Oshikawa; Kohei Motomura; Toshimitsu Komatsu
Linked Author(s): Hideo Oshikawa
Keywords: Submerged asymmetric structure; Wave field; Residual current; Dimensionless parameter; Empirical formula; BaNK system
Abstract: Residual currents around submerged asymmetric structures known as Beach and Navigation Keeper (Ba NK) blocks are quantitatively estimated in wave fields. The Ba NK system has been proposed in order to cope with beach erosion and shoaling of fairways. The system is a method for controlling sediment transport by using residual currents that are produced by multiple submerged asymmetric structures in a wave field. In this study, three dimensionless parameters, namely, the Keulegan-Carpenter number, Reynolds number, and structure height relative to water depth, are considered as the main dimensionless parameters for producing residual currents. Velocity distributions around half-cylinder Ba NK blocks are measured for various wave conditions and structure heights in a wave tank. The relations between vertical residual current distributions around asymmetric structures and the dimensionless parameters are found. Furthermore empirical formulas are established to calculate residual currents generated by the Ba NK system in a wave field.
Year: 2012