Smoke Flow Visualization of Dragonfly Pantala Flavescens in Tethered Flight

Dragonflies use unsteady mechanisms, like leading-edge vortex (LEV) and trailing-edge vortex (TEV), to generate high lift in a few wing beats to perform flight maneuvers and hunt smaller insects. We qualitatively study flow field and topology using smoke flow visualization and high-speed imaging over dragonfly species Pantala flavescens. We observed LEV, TEV, stagnation point, saddle point, and a vortex loop in the wake formed by the interaction of LEV and TEV. We observe that LEVs remain attached to the wings at very high angles of attack due to active control of the flexibility of the wings.