Wake classification of heaving airfoils using the spectral/hp element method

In this paper, the two dimensional unsteady flow over a heaving NACA0012 airfoil is simulated using a high-order numerical method associated with a moving frame of reference technique, in order to obtain more accurate and high resolution data. This data can be used to characterize oscillating airfoil wakes with very fine temporal and spatial details. The mean incidence investigated is α¯=0° and Reynolds number Re=104. The transition from a drag-producing wake, to a neutral, and a thrust-producing wake is observed and analyzed. The results obtained are in accordance with previously published experimental and computational investigations. Furthermore, a more detailed wake classification is presented, where two new wake configurations are captured. The role of the trailing-edge, and the interaction of the natural shedding frequency of the airfoil and the imposed forcing frequency in the creation of multiple-vortices-per-half-cycle shedding mode are investigated. The relation between the interaction of the two aforementioned frequencies and the observed shedding modes is established.