On the coupling of vortex flow and whisker sensor in the wake of moving objects

In this study, we studied the wake-induced vibration (WIV) of a whisker model in the wake of a moving circular cylinder with various initial gap distances and moving speeds. Time-resolved particle image velocimetry was used to capture the synchronized wake dynamics and vibrations of whisker. Before the movement of circular cylinder, vibrations of whisker exhibited typical 'slaloming' patterns across all tested gap distance. After the movement of cylinder, the vibration amplitude decreased with the increasing gap distance, and the decaying rate was determined by the coupled influence of initial vortex strength and gap distance growth rate. A model based on harmonic oscillator with rational decaying force coefficient was provided to predict the time series of whisker WIV. To further explore the influence of vortex shedding patterns on WIV of whisker, off-centered whisker was placed in the wake of the moving cylinder as comparison. Before the movement of cylinder, the off-centered whisker vibrated at an equilibrium position that deflected toward the flow center; as the gap distance increased, whisker gradually moved back to its off-centered neutral, this trend was accompanied with faster vibration decaying due to lower initial vortex strength.