Self-excited aeroelastic instability of a flexible cantilever cylinder at laminar subcritical Reynolds number

Fluid-structure interaction of a flexible cantilever cylinder with the surrounding flow is ubiquitous in nature and present in many engineering systems. In particular, the FSI of a rat's whisker with low-speed airflow has gained importance in recent years due to its implications for the development of novel flow-measurement sensors. A rat's whisker interacting with airflow at laminar subcritical Reynolds numbers, (i.e., no periodic vortex shedding) has been shown to undergo sustained large-amplitude oscillations (i.e., self-excited aeroelastic instability) that carry information about the direction and magnitude of the airflow. In this work, we use high-fidelity numerical simulations to examine the aeroelastic instability of a flexible cantilever cylinder with a constant circular cross-section, as a canonical model of a whisker. Through a parametric investigation, we assess the self-excited instability of the cylinder and highlight the key aspects of the fluid-structure system. We show that the cylinder could undergo sustained oscillations when certain conditions are satisfied. The amplitude of the oscillations is found to be a function of flow velocity and the frequency of the perturbation in the flow field.