Flow field and vortical structures around a vertical cylinder with cyclic lateral vibration

The flow around a cylinder subjected to cyclic lateral vibration along its entire length has been extensively studied. However, cyclic lateral vibrations imposed specifically at the top of cylindrical structures, resulting from hydrodynamic-structure coupling or complex dynamic environments, present a more realistic scenario in actual engineering practice. Research specifically examining the flow characteristics around cylindrical structures under such localized top vibrations remains relatively limited. To address this gap, this study numerically investigates the flow field and vortical structures around a cylinder subjected to cyclic lateral vibration using OpenFOAM. The numerical model was verified by physical experiment results, and the verification indicates a good performance of the modeling. The results show that vibrations at the cylinder's top significantly impact both flow dynamics and vortex shedding patterns. Specifically, the vibrations weaken downflow intensity and reduce kinetic energy transfer to horseshoe vortices (HSVs), resulting in smaller HSVs and lower bed shear stress upstream. Furthermore, the study identifies various vortex shedding modes, with shedding primarily occurring when the cylinder vibrates downstream at its maximum velocity. The increase in vibration amplitude broadens the drag coefficient's fluctuation range, especially affecting the minimum values. This research elucidates the effects of vibration on the ambient flow field and provides insights into fluid–structure interactions.