SIMULATION OF DYNAMIC STALL PHENOMENON USING UNSTEADY NAVIER-STOKES EQUATIONS

A non-inertial body-fixed generalized coordinate frame is employed to develop an unsteady Navier-Stokes (NS) analysis for arbitrarily maneuvering bodies. A fully implicit direct numerical simulation (DNS) methodology is implemented for the solution of the governing equations. A velocity-vorticity (disturbance stream function - vorticity in 2-D) formulation is shown to simplify both the theoretical and numerical analysis of maneuvering flight when compared with the primitive-variable formulation. The resulting numerical method is highly vectorizable and currently achieves a computational index of 6 micro-seconds per time step per mesh point using a single processor on the CRAY Y-MP 8/864 at the Ohio Supercomputer Center. Vectorization has been achieved satisfactorily, with the code currently performing in the range of 130-180 Mflops. The rapid pitch-up maneuver of a NACA 0015 airfoil is examined at Re = 1000 and Re = 10 000, with particular emphasis being placed on the development and evolution of the dynamic stall vortex.