Flight force production by flapping insect wings in inclined stroke plane kinematics

The unsteady flow structure and the time-varying aerodynamic forces acting on a 2D dragonfly model wing are studied by numerically solving the Navier-Stokes equations. The incompressible Navier-Stokes equations are discretized and solved on a non-body confirming Cartesian grid; the concept of immersed boundary method is made use of to impose the no-slip boundary condition on the surface of the wing. The objective of the present study is to investigate the influence of the following kinematic parameters on the flight performance of inclined stroke plane hovering: Reynolds number (Re), stroke amplitude, wing rotational timing and rotational duration. While the effects of the above mentioned parameters on the stroke averaged force coefficients are the same in both horizontal and inclined stroke plane motions, the spatiotemporal dynamics of vorticity which produce the effects are entirely different. Our results also indicate that the drag mechanism proposed for tiny insects does not seem to augment the vertical force generation in inclined stroke plane motion. © 2009 Elsevier Ltd. All rights reserved.