  The expanding application in Micro-Air Vehicles has encouraged many
researchers to understand the unsteady flow around a flapping foil at a low
Reynolds number. We numerically investigate an incompressible unsteady flow
around a two-dimensional pitching airfoil (SD7003) at high reduced frequency in
the laminar regime. This study interrogates the effect of different unsteady
parameters, namely amplitude (A), reduced frequency (k), Reynolds number (Re),
and asymmetry parameter (S) for pitching motion on the force coefficients. The
inviscid theoretical model is utilized to calculate the lift coefficient for
sinusoidal motion in the viscous regime, and a comparison is made with the
numerical results. The theoretical analysis identifies the influence of the
non-circulatory lift over circulatory lift at a high reduced frequency.
Further, the results indicate that the reduced frequency (k) and asymmetry
parameter (S) have a significant impact on the instantaneous and time-averaged
force coefficients as well as on the vortex structure in the wake. Finally, the
Fast Fourier Transformation (FFT) analysis is carried out over a simulated case
with fixed amplitude and Reynolds number for distinct k and S values. The
findings confirm that the dominant frequency in the flow (k*) has a direct
correlation to the airfoil pitching frequency (k).
