Experimental and numerical investigation of the interaction between extreme waves and composite large-diameter cylindrical breakwater

The widespread application of large-diameter cylinders in offshore cofferdams highlights their potential as breakwater structures. Understanding the wave attenuation characteristics of large-diameter cylindrical breakwaters is fundamental to further applications. Existing studies are mainly focusing on small-diameter cylindrical breakwaters and non-extreme wave conditions. Hence, a novel large-diameter cylindrical breakwater (CLCB) is proposed by integrating the side plate, crown wall and apron into large-diameter cylinders. A set of wave flume experiments on the hydraulic performance of CLCB under extreme wave conditions were conducted. The reliability of the developed numerical model is revealed based on a series of model validations. A comprehensive analysis is conducted to investigate the effects of different structure parameters on wave attenuation performance. The simulation results indicate that increasing the height of the side plate and crown wall could significantly decrease the wave transmission coefficient, while variations in apron height have a limited influence. Within the parameters utilized in this investigation, CLCB demonstrates superior wave attenuation performance under extreme wave conditions, better than that under non-extreme wave environments. The results from this study optimize the design of large-diameter cylindrical breakwaters and generate new insights into the interaction between large-diameter cylindrical breakwaters and extreme waves.