Immersed-boundary methods have been proposed to provide powerful simulation tools for flow interacting with moving and morphing structures. They are therefore particularly useful for studying flapping-wing micro-aerial vehicles. However, the merit of this type of methods has yet to be approved by validation with measurement data or other types of simulation. On the other hand, the simulation can be used to investigate the applicability of the classical theoretical models for predicting unsteady

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... aerodynamic behaviors of flapping airfoils. In this paper, a set of canonical cases of flapping airfoil motions are simulated using an improved immersed-boundary method. These cases have been selected as candidates for a group study using different measurement methods as well as simulation methods. The results of our simulation are compared with measurement and simulation results by other simulation methods to address the merit of our simulation. Furthermore, the results from classical theories, such as those of Theodorsen and Garrick for flapping wings, are compared to investigate the effect of circulatory and non-circulatory flow dynamics on the lift and drag of fast pitching airfoils. Nomenclature u = velocity vector (u,v) P = pressure Re = Reynold's number, based on the chord length of the airfoil; Re=1000 for all the simulation here f = boundary forcing term