Numerical study of kinematic wing models of hovering insect flight

The influence of different wing kinematic models on the aerodynamic performance of a hovering insect is investigated by means of two-dimensional time-dependent Navier-Stokes simulations. For this, simplified models are compared with more realistic representations of the hovering fruit fly wing kinematics. With increasing complexity, a harmonic model, a Robofly model and two more realistic fruit fly models are considered, all dynamically scaled at Re = 110. To facilitate the comparison, the parameters of the models were selected such that their mean quasi-steady resultant force coefficient were matched. Details of the vortex dynamics, as well as the resulting lift and drag forces were studied. The simulation results reveal that the simplified wing kinematics result in forces that differ significantly from those resulting from the actual fruit fly wing kinematic models. In addition, the flow simulation results shed light on the effect of different characteristic features of the insect wing motion. The angle of attack variation used by real fruit flies increases aerodynamic performance, whereas the deviation is most likely used for leveling the forces over the cycle.