Direct Numerical Simulations on the three-dimensional wake transition of flows over NACA0012 airfoil at Re=1000

For micro air vehicles (MAV), the precise prediction of aerodynamic force plays an important role. The aerodynamic force of a comparative low Reynold number (Re) vehicle tends to be affected by the different flow modes. In this paper, the aerodynamic performance of a three-dimensional NACA0012 airfoil is studied numerically. A range of angles of attack (alpha) 0 degrees-25 degrees and Reynolds number 1000 is considered. Mean and fluctuating coefficients of aerodynamic forces around NACA0012 airfoil are analyzed for different wake modes. The difference of aerodynamic forces between two and three-dimensional simulations are compared. The results show that the wake remains steady two-dimensional for lower angles of attack. At alpha = 9 degrees, Von Karman vortex pattern is noticed. Flow transition to three-dimensional as the angle of attack increases from alpha = 13 degrees. 3D wake is found to be stable with parallel shedding mode for 14 degrees-17 degrees. However, these modes become finer with the gradual increase in angle of incidence. While, wake loses its three-dimensional stability to chaotic with gradual increment in angle of attack afterwards.