Meeting Abstract
The flexibility of the flukes has been found crucial in cetaceans’ propulsion. Previous research (Fish et al., 2005) has shown both the chordwise and spanwise flexibility could increase thrust generation in swimming dolphins. In this work, we examined the effect of fluke flexibility on the hydrodynamic performance and flow modulation in a freely swimming orca, which has demonstrated substantial spanwise bending in the oscillatory cycle. Using a combined experimental and computational approach, we first quantified the dynamic cambering and bending of the fluke in a complete oscillatory cycle during the steady swimming. It’s found that the fluke presented larger spanwise bending during the upstroke, and smaller chordwise cambering during the downstroke. This resulted in an effective flow modulation and thus enhanced the fluke’s propulsive performance. Further 3D vortex dynamics analyses have shown the key propulsion mechanism in orcas. Findings from this work are fundamental to understand key kinematic features of cetacean propulsors, and for quantifying the hydrodynamic force production that naturally occurs in cetaceans’ steady swimming. (This work is supported by ONR MURI N00014-14-1-0533 and AFOSR FA9550-12-1-0071)
