Controlling flow separation with backward traveling waves: from a turbulent channel flow to a low Reynolds number airfoil *

The flow over many aquatic swimmers’ bodies is attached as they propel themselves via backward traveling waves. ‎Inspired by aquatic animals, large eddy simulations (LES) of a turbulent channel flow which its wall is undergoing ‎an undulatory motion are performed to investigate the effect of the wave on the flow dynamics. Effect of ‎different wave speed and amplitude on flow separation is investigated. The results show the reverse flow in the ‎wavy channel decreases when the wave speed increases. To see if the undulatory oscillation can also improve ‎the aerodynamic characteristics of an airfoil, similar low amplitude traveling wave oscillations which ‎can be generated experimentally are performed over the suction side of the airfoil. The Reynolds number (Re) is 50,000 ‎and the angle of attack is ten degrees in these simulations. The results show that the traveling wave oscillation can increase the ‎lift by 8% by consuming a negligible energy to produce the wave.