Efficient Flapping Flight Using Flexible Wings Oscillating at Resonance

We use fully-coupled three-dimensional computer simulations to examine aerodynamics of elastic wings oscillating at resonance. Wings are modeled as planar elastic plates plunging sinusoidally at a low Reynolds number. The wings are tilted from horizontal, thereby generating asymmetric flow patterns and non-zero net aerodynamic forces. Our simulations reveal that resonance oscillations of elastic wings drastically enhance aerodynamic lift, thrust, and efficiency. We show that flexible wings driven at resonance by a simple harmonic stroke generate lift comparable to that of small insects that employ a significantly more complicated stroke kinematics. The results of our simulations point to the feasibility of using flexible resonant wings with a simple stroke for designing efficient microscale flying vehicles.