A numerical analysis of wave type and steepness effects on cylindrical buoy dynamic characteristics

In the intricate realm of ocean-atmosphere dynamics, the sustained and stable operation of buoy observation systems under rough seas is crucial for ensuring marine resource security. This study employs a coupled Level-Set and Volume of Fluid (CLSVOF) method alongside the immersed boundary method. It investigates the physical processes of wind-wave interaction, the dynamic characteristics of cylindrical buoys, as well as the underlying mechanisms. The research highlights the significant impact of wave types (wind waves, swells) and wave steepness on the buoy's drift and oscillatory behavior. An increase in wave steepness and a shift from wind waves to swell markedly intensify both the buoy's drift and its oscillatory motions. Additionally, a thorough analysis of the loads on the buoy under varying maritime conditions is performed. By examining the vertical momentum equation on the windward and leeward sides, the secondary load cycle phenomenon is found to originate from collapse of the water column formed by the convergence of water flow behind the buoy. Wind waves are found to be less conducive to secondary load cycles compared to swell waves. Furthermore, the study investigates the relationship between the drag coefficient and the wave crest height on the windward side of the buoy, revealing a robust negative correlation between the two. This research not only illuminates the complex dynamics of windwave couplings but also offers theoretical insights for the optimization of buoy design.