Experimental visualization of three-dimensional flow using flapping model mimicking free-flight of dragonfly by tomography

Abstract

Dragonflies generate three-dimensional flow to gain aerodynamic forces. However, three-dimensional flow in free-flight of dragonfly is not clarified experimentally. In this study, experimental visualization and particle image velocimetry (PIV) analysis using tomography is carried out to clarify experimentally the three-dimensional flow. The flap simulator mimicking flapping motion of dragonfly is used for visualization because reproducible measurement is important for tomography. The flow is visualized with tomography from front and lateral side of the flap simulator. As a result, straight flight of dragonfly generates swift flow in a posterior direction in the center on the direction of wingspan. Moreover, it is confirmed that the flow is drawn to base-side of wings. It is suspected that the flow pulled by the flow in a posterior direction. Therefore, straight flight of dragonfly does not generate the extra flow in the direction of wingspan and generates the swift flow in a posterior direction.