Abstract: In the work, it is shown the numerical investigations about the unsteady inviscid results obtained for the pitching oscillating wings at different angles of attack. The results are obtained by solving the unsteady Euler equations in a body_fitted coordinate system. It is based on the four_stage Runge_Kutta time stepping scheme. Meanwhile to increase the time step that is limited by Courant limit(CFL), the implicit residual smoothing with local variable parameters is used. As a result, the unsteady aerodynamics about a rectangular wing and a delta wing, which are oscillated in pitching with different frequencies, are shown in this paper. The properties of the unsteady aerodynamics in these cases are researched here.

Key words: unsteady flow, hysteresis, high angle of attach, vortical flow