Wake-Induced Vibrations of a Whisker-Inspired Sensor Array

Harbor seal whiskers have been of great interest for their ability to distinguish wake-induced vibrations from vortex-induced vibrations from upstream objects. This study uses an array of biologically inspired whisker sensors that consist of a resin-printed whisker mounted onto a polydimethylsiloxane (PDMS) base embedded with two strain gauges to measure streamwise and transverse strain. The array was placed at varying transverse and streamwise distances downstream from a source object that produces a periodic wake, such as a stationary cylinder, a pitching foil, and a propeller. Strain data were collected for each source object at Reynolds numbers O(10³) to O(10⁴). Due to the relative position with respect to the wake, each sensor experiences a different hydrodynamic force and thus creates both a spatial and temporal perception of the flow field. Power spectral density (PSD) analysis and dynamic mode decomposition (DMD) were used to extract dominant features and characterize the sensors’ ability to resolve wake signals in terms of sensitivity, directionality, and the signal-to-noise (SNR) ratio. We show that the information from an array of sensors provides additional information about the wake source compared to an individual sensor. Moreover, we find that the information of the array can be used to disambiguate source objects producing oscillatory wakes at the same frequency.