Unsteady Aerodynamic Effects of Wing-body Interactions in Three-dimensional Insects' Flapping Flight

Abstract

This paper investigates the unsteady aerodynamic features of wing-wing, wing-body and vortex-vortex interactions in insects' flapping motions under forward flight condition. A realistic wing trajectory, called the figure-of-eight motion, is extracted from a blowfly (Phormia regina)s tethered flight experiment under the freestream velocity of 2.75m/s. Since the flow field around the blowfly exhibits characteristics of low-Reynolds number flow, the three-dimensional unsteady incompressible Navier-Stokes equations are employed as the governing equations. In order to simulate the realistic insect flapping flight including geometric and kinematical complexity with a sufficient level of grid quality, overset grid technique is used. From the authors' previous researches on two- and three-dimensional rigid wing simulation, it has been observed that the pattern of vortical flows and the interaction of vortices play an important role in generating unsteady aerodynamic forces and determining the propulsive efficiency of flapping motion. Detailed numerical simulations of a blowflys wing-body motion are conducted to examine unsteady flow features resulted from the wing-body interaction.