Unsteady Aerodynamics of a Wing-in-Ground-Effect Airfoil Flying over a Wavy Wall

Aerodynamic characteristics of an airfoil, the NACA 6409, flying over a wavy wall is investigated numerically. An Euler code based on the LU-factored algorithm and higher-order upwind scheme is constructed and its accuracy is tested with three benchmark problems: a NACA 4412 airfoil moving over a level ground, a NACA 0012 airfoil in free-flight pitching oscillation, and a NACA 0012 airfoil flying over a wavy wall. The calculated flow about NACA 6409 airfoil over the wavy ground represented by a moving sine function indicates that the aerodynamic property of the airfoil becomes sensitive if the wave number or amplitude of the wavy ground is increased and/or if the proximity of the airfoil to the ground is lowered