Aerodynamics of a wing under figure-of-eight flapping motion: FSI simulations

This paper investigates the aerodynamics of a wing under figure-of-eight flapping motion based on Fluid–Structure Interaction (FSI) Computational Fluid Dynamics (CFD) simulations. The kinematic of a wing under figure-of-eight motion creates a condition with a variable angle-of-attack. The effect of using different angles of attack at an initial condition, namely initial pitch angles, for the wing and the spatial size of the figure-of-eight pattern, namely the input link angle, is investigated. The initial pitch angles input is varied from 0° to 330° in steps of 30°, and the input link angles used are 30°, 45°, and 60°. The Young’s modulus of the wing is 3.4 GPa spanwise, which is the elastic modulus of balsa wood material. In comparison with an initial pitch angle of 0°, the 90° initial pitch angle shows much better flight performance in terms of lift generated and stability. The results show that the maximum average lift coefficient of 0.393 occurs at the 90° initial pitch angle. The maximum lift-induced moment for the 90° initial pitch angle is only 5.55% of the maximum lift induced moment for the 0° initial pitch angle. A higher input link angle generates a greater lift force. The pressure distribution in the vicinity of the wing area and the von Mises stress of the wing are also presented.