Passive wake detection using seal whisker-inspired sensing
type: CreativeWork
description: This thesis is motivated by biological experiments, which display the harbor seal's ability to track the wake of an object several seconds after it swam by. In this work, I elucidate the basic fluid mechanisms that seals may employ to accomplish this detection. Key are the unique vortex-induced vibration (VIV) properties resulting from the geometry of the harbor seal whisker. First, force measurements and flow visualizations on a rigid whisker model undergoing 1-D imposed oscillations show that the geometry passively reduces VIV (factor of >10), despite contributions from effective added mass and damping. This suggests that harbor seal whiskers would detect details of the oncoming flow with reduced background “noise". Next, a biomimetic whisker sensor is designed by mounting the model on a four-armed flexure, allowing it to freely vibrate, and using strain gauges to measure deflections at the whisker base. Finally, this whisker device is towed behind an upstream cylinder with larger diameter. In the wake, the whisker oscillates with large amplitude and at the Strouhal frequency of the upstream cylinder. A slaloming motion among the wake vortices drives this interaction, and it enables detection of the upstream wake.
abstract: This thesis is motivated by biological experiments, which display the harbor seal's ability to track the wake of an object several seconds after it swam by. In this work, I elucidate the basic fluid mechanisms that seals may employ to accomplish this detection. Key are the unique vortex-induced vibration (VIV) properties resulting from the geometry of the harbor seal whisker. First, force measurements and flow visualizations on a rigid whisker model undergoing 1-D imposed oscillations show that the geometry passively reduces VIV (factor of >10), despite contributions from effective added mass and damping. This suggests that harbor seal whiskers would detect details of the oncoming flow with reduced background “noise". Next, a biomimetic whisker sensor is designed by mounting the model on a four-armed flexure, allowing it to freely vibrate, and using strain gauges to measure deflections at the whisker base. Finally, this whisker device is towed behind an upstream cylinder with larger diameter. In the wake, the whisker oscillates with large amplitude and at the Strouhal frequency of the upstream cylinder. A slaloming motion among the wake vortices drives this interaction, and it enables detection of the upstream wake.
author: Beem, Heather R.
language: en_US
keywords: Wecoma (Ship) Cruise W1109C, Wakes, Harbor seal, Behavior
date published: 2015-02
date modified: 2026-07-27T22:05:02Z
provider: Woods Hole Oceanographic Institute
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Massachusetts Institute of Technology and Woods Hole Oceanographic Institution

PropertyValue
property ID: Handle
value: https://hdl.handle.net/1912/7124

PropertyValue
property ID: DOI
value: 10.1575/1912/7124