Numerical investigation of the flow pattern around a vertical cylinder under wave action

The interaction between vertical cylinders and waves is an important research problem due to the prevalence of cylinder-type structures in marine infrastructure. A major goal is to improve their design for greater stability in the presence of waves. In this study, we numerically investigate the formation of vortices around a vertical cylinder under wave action, emphasizing the role of the flow field in potential bed erosion. Surface pressure distribution analysis elucidates the generation and evolution of the vortices, while the spatial distributions of bed shear stress quantify the significant influence of the flow field and vortex dynamics on scour around the cylinder. Numerical simulations were performed over a range of Keulegan-Carpenter (KC) numbers (12–26) to systematically resolve the 3D flow structures. Validation against particle image velocimetry (PIV) data confirms the accuracy of these simulations. Our results show that both the strength and spatial extent of the horseshoe vortex increase markedly with increasing KC number, leading to intensified bed shear stress and elevated scour potential around the cylinder.