Hydrodynamics of aquatic swimming: inspiration for flow control

Aquatic swimming has fascinated researchers for more than a century. In this keynote talk, different types of swimming, their mechanisms of propulsion, and major findings from simulations are reviewed. The body undulations of the fish, which can be approximated well by a backward traveling wave, tend to keep the flow attached on the body of the swimmer. These observations have inspired us to use low-amplitude, backward traveling waves (which can be generated through piezoelectric actuators) for flow control. Our results indicate that backward traveling waves perform better than other types of surface morphing, e.g., standing waves, to control the flow separation over an airfoil.