Rotational movement of a harbor seal whisker during vortex induced vibrations

Abstract

Harbor seal whiskers have geometry that reduces vortex induced vibrations. Previous experiments with rigid models of the harbor seal whiskers has shown that the reduced vibration of the whisker can be used to detect the wake of other objects in water. This project focused on expanding the experiments done with the rigid whisker by adding the ability to rotate to the whisker. A rubber whisker was used to explore the response of a fully flexible whisker as it was dragged through water and tracked optically. This was compared with the results from previous experiments. Then a new rigid whisker sensor was created that allowed the whisker to rotate as well as vibrate. Experiments with this whisker holding it to rotation only, rotation with spring force, and rotation with vibration showed that the whisker experienced the effects of the Munk moment at higher speeds when allowed to vibrate, also the rotational vibration of the whisker was noisy except when allowed to vibrate in the crossflow direction. Further work could be done to improve the capability to detect the rotational position of the rigid whisker without introducing excess friction to the system.