The visualization experiment and theoretical analysis of the flow field of honeybee flapping-wing

The goal of this study is to show characteristics of flow field of honeybee wings' flapping with performing multiple sets of flow visualization experiment in low-speed smoke tunnel. Periodic flow field structures of far and near field of the honeybee were imaged using high-speed camera,and leading edge vortex,trailing edge vortex and wing tip vortex were analized.At the trailing edge of the wing, the downstroke stopping vortex and upstroke starting vortex were generated at the end of the down stroke. Both the forewing and hindwing could flex and rotate at the stroke reversal, leading the circular rectors of the trailing edge vortex of the forewing and hindwing to be in the opposite direction. The size of the leading edge vortex was increasing from wing root to wing tip, and the spanwise flow structure was composed of leading edge vortex and trailing edge vortex. At the end of the down stroke, the scroll generated by the wing tip vortex was connected with the wing margin circular rector, respectively forming the independent vortex rings on right and left wings. Meanwhile downstroke lift was estimated utilizing the vortex ring theory.