Swept Back Angle Induced Spanwise Force Variation on a Seal Whisker Inspired Geometry*

Seals possess undulated whiskers, distinct from the smooth whiskers of other mammals, that aid them in navigation and prey tracking. Results show that the opposing dual spanwise undulations on the whisker surface are responsible for a 10.4% reduction in drag and 91.2% reduction in oscillating lift forces resulting from the modified vortex shedding as compared to a streamlined ellipse of equivalent dimensions. Although most prior research has investigated flow perpendicular to the whisker span, seal whiskers experience a wide range of orientations with respect to incoming flow as the animals navigate their environment. The focus of this work is the exploration of whisker swept flow angles resulting from both the deliberate relaxation and protraction of whiskers and by material bending in response to drag forces. The complex surface undulations of the whisker create three-dimensional flow behaviors and modification of forces that vary significantly with sweep angle. This variation has implications in seals’ sensing behavior as well as the potential applications of whisker geometry for drag and lift force reduction. To understand the effects of this orientation change, direct numerical simulations of flow over model whisker surfaces at swept back angles are performed. These simulations are used to extract force and shedding frequency data across spanwise segments to understand the mechanisms responsible for the significant reduction in forces and modification to shedding behavior uniquely attributed to this geometry at sweep angles.