Asymmetric sinusoidal motion effect on aerodynamics of a plunging airfoil

The effect of asymmetric sinusoidal motion on plunging airfoil aerodynamics was studied by numerical simulations for 2-D flow around a NACA0012 airfoil at Re=1.35×10₅. Various unsteady parameters (nondimensional plunging amplitude, h, reduced frequency, k) were applied to investigate the effect of asymmetry parameter S on the instantaneous force coefficient and flow pattern. It is found that more thrust can be generated by asymmetric sinusoidal plunging motion compared with pure sinusoidal case, and the thrust force generated increases with asymmetry. Moreover, a significant difference in the wake pattern at different values of S is observed. The trailing wake is displaced downward relative to the free stream for S less than 0.5, and displaced upward for S larger than 0.5.