Accession Number : ADA613230


Title :   Passive Wake Detection Using Seal Whisker-Inspired Sensing


Descriptive Note : Doctoral thesis


Corporate Author : MASSACHUSETTS INST OF TECH WOODS HOLE MA DEPT OF APPLIED OCEAN PHYSICS AND ENGINEERING


Personal Author(s) : Beem, Heather R


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a613230.pdf


Report Date : Feb 2015


Pagination or Media Count : 198


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.


Descriptors :   *BIOMIMETICS , *WAKE DETECTION , DEFLECTION , FLOW , MEASUREMENT , OSCILLATION , PASSIVE SYSTEMS , SEALS(MAMMALS) , STRAIN GAGES , TRACKING , VIBRATION


Subject Categories : Non-acoustic and Non-magnetic Sub Detection
      Miscellaneous Detection and Detectors
      Bionics


Distribution Statement : APPROVED FOR PUBLIC RELEASE