Effects of Unequal Pitch and Plunge Airfoil Motion Frequency on Aerodynamic Response

Departing from mainstream pitching/plunging airfoil literature, we consider scenarios where the frequencies of the plunge and the pitch are not equal. The motivation is, first, consideration of flows with very large excursions in total angle of attack, for assessment of motion time history effects; and second, an attempt to model the gust response of flapping-wing Micro Air Vehicles by considering the higher-frequency motion as the prototype kinematics for the flapping, and the lower-frequency motion as prototype for the gust. Computations with immersed boundary methods at Re < 1000 are compared with water tunnel experiments at Re = 10,000. Despite the enormous difference in Reynolds number, qualitative behavior of vortex shedding was found to be very similar, with implications of broadening the scope of very low-Re simulations for such flows in general.