Fast and efficient underwater propulsion inspired by biology
Alexander J. Smits
Eugene Higgis Professor, Department of Mechanical and AerospaceEngineering, Princeton University
Biology offers a rich source of inspiration for the design of novel propulsors with the potential to overcome and surpass the performance of traditional propulsors for the next generation of underwater vehicles. To-date, however, we have not achieved the deeper understanding of the biological systems required to engineer propulsors with the high speed and efficiency of animals like sailfish, tuna, or dolphins. What is the underlying physics of the fluid-structure interaction of bio-propulsors that results in the superior performance observed in nature? Moreover, how do we replicate this performance in the next generation of man-made propulsors? Can we push beyond the limits of biology? By studying the performance of simple heaving and pitching foils, we have identified the basic scaling that describes the thrust, power and efficiency, under continuous as well as burst-coast actuation. These scaling relationships allow us to identify the natural limits on simple bio-inspired propulsors, and suggest that further improvements in performance will require adaptive flexibility and optimized planforms.