Laboratory studies of breaking wave forces acting on vertical cylinders in shallow water

In some locations, the best way to create a deep water port is to construct on off-shore berth which is joined to the land by a jetty. Such jetties are usually supported on piles and these are often subjected to breaking waves. Dimensional analysis indicates that for smooth circular cylinders the total wave forces and the moments from depth limited waves may be calculated as functions of parameters which, except for Re, can be measured directly [F, M=f(d/Lo, Ho/Lo, D/Ho, S, Re)]. Since the maximum force is experienced at a definite location, the parameter d/Lo is implied in the parameters S and Ho/Lo. The investigations reported in this paper were based on hydraulic model tests with regular waves and present the magnitudes of the relative breaking wave force and moment in the breaking wave zone as functions of these parameters. From the results of experiments with two cylinder diameters, D=0.102 and 0.153 m, carried out in three different wave channels, empirical formulae for force and moment have been established with the deep water wave steepness, Ho/Lo, and the relative cylinder diameter, D/Ho as independent variables. These apply to specific bottom slope of S=1:15. The experimental range compares to drag dominated condition and a Reynolds number range 0.6×105