Runup and Rundown Characteristics of an Emerged Seaside Perforated Quarter Circle Breakwater

Quarter circle breakwater (QBW) is developed from semicircular breakwater (SBW) and the first model was developed in Peoples Republic of China. The superstructure of QBW consists of a quarter circular front wall facing incident waves, a horizontal base slab and a vertical rear wall placed on rubble mound foundation. A series of experiments were conducted in a two dimensional regular wave flume available in Marine structures laboratory of Department of Applied Mechanics and Hydraulics of National Institute of Technology, Surathkal, Karnataka to assess the wave runup and wave rundown characteristics of an emerged seaside perforated quarter circle breakwater. Quarter-circle breakwater models with three different radii and S/D (spacing to diameter of perforations) ratio equal to 5 were tested. The data collected was analyzed by plotting the graph of dimensionless wave run up, Ru/Hi (where Ru= runup and Hi= incident wave height) and dimensionless wave rundown, Rd/ Hi (where Rd = wave rundown and Hi= incident wave height) for various values of wave steepness, Hi/gT2 and different height of structure to the depth of water (hs/d) values. The dimensionless wave runup, Ru/Hi increases with the increase in the wave steepness and also it increases with the increase in hs/d but the dimensionless wave rundown, Rd/Hi decreases with the increase in the wave steepness and also it decreases with the increase in hs/d.