  The unsteady aerodynamic thrust and aeroelastic response of a two-dimensional
membrane airfoil under prescribed harmonic motion are investigated
computationally with a high-order Navier-Stokes solver coupled to a nonlinear
membrane structural model. The effects of membrane prestress and elasticity are
examined parametrically for selected plunge and pitch-plunge motions at a
chord-based Reynolds number of 2500. The importance of inertial membrane loads
resulting from the prescribed flapping is also assessed for pure plunging
motions. This study compares the period-averaged aerodynamic loads of flexible
versus rigid membrane airfoils and highlights the vortex structures and salient
fluid-membrane interactions that enable more efficient flapping thrust
production in low Reynolds number flows.
