Wavy Whiskers in Wakes: Explaining the Trail-Tracking Capabilities of Whisker Arrays on Seal Muzzles

Seals can detect prey up to 180 m away using only their flow-sensing whiskers. The unique undulating morphology of Phocid seal whiskers reduces vortex-induced vibrations (VIVs), rendering seals highly sensitive to biologically relevant flow stimuli. In this work, digital models of harbor and grey seal whiskers are extracted using 3D scanning and a mathematical framework that accurately recreates their undulating geometry is proposed. Through fluid-structure interaction studies and experimental investigations involving a whisker array mounted on 3D-printed microelectromechanical systems sensors, the vibration characteristics of the whisker array and the interaction between neighboring whiskers in steady flows and fish-wake-like vortices are explained for the first time. Results reveal that the downstream vortices intensity and resulting VIVs are consistently lower for grey than harbor seal whiskers and a smooth cylinder, suggesting that the grey seal whisker geometry can be an ideal template for the biomimetic design of VIV-resistant underwater structures. In addition, neighboring whiskers in an array influence one another by resulting in greater flow vorticity fluctuation and distribution area, thus causing increased vibrations than an isolated whisker, which indicates the possibility of a signal-strengthening effect in whisker arrays.

Automated summary

Seals can detect prey up to 180 m away using their flow-sensing whiskers. The undulating morphology of their whiskers reduce vortex-induced vibrations, making them highly sensitive to biologically relevant flow stimuli. This study proposes a mathematical framework to accurately recreate the undulating geometry of harbor and grey seal whiskers. The research also reveals that grey seal whiskers have lower vortex-induced vibrations compared to harbor seal whiskers and a smooth cylinder, making them an ideal template for the biomimetic design of VIV-resistant underwater structures. Additionally, neighboring whiskers in an array influence each other, leading to increased vibrations and a possible signal-strengthening effect.