Meeting Abstract

P1.193  Friday, Jan. 4  Aerodynamic performance of gliding dragonflies with three-dimensional corrugated wings NAKATA, T.*; HENNINGSSON, P.; LIU, H.; BOMPHREY, R.J.; Univ. of Oxford; Univ. of Oxford; Chiba Univ.; Univ. of Oxford toshiyuki.nakata@zoo.ox.ac.uk

Dragonfly wings are not smooth surfaces but have distinct corrugations that stiffen the wings against high aerodynamic and inertial bending moments. Corrugations may also directly enhance the aerodynamic characteristics of the wings by modifying lift to drag ratios or indirectly by enabling high aspect ratios – thereby reducing induced drag – without greatly increasing material volume or spanwise torsional stiffness. The aerodynamic effect of insect wing corrugations in gliding or flapping flight has been reported previously with most analyses performed in two-dimensions or three-dimensions based on extrusions of a common corrugated profile along the wings’ length, overlooking the consequences of spanwise variation in corrugation pattern and three-dimensional aerodynamic effects. In this study, a computational fluid dynamic analysis of gliding dragonflies was performed using a selection of three-dimensional wing shapes measured as a series of cross-sections along the wing span, by projecting a laser light sheet onto the wing surfaces of museum specimens and freshly captured individuals and recording the topography using a digital camera. Corrugation was digitally reconstructed from the laser scan images and found to vary markedly along the spanwise axis.Its effect on aerodynamic performance was evaluated by comparing the full-fidelity models with alternative wing topographies. The results indicate that the inherent corrugation in dragonfly wings does not lead to an abrupt decrease in aerodynamic performance and may be a compromise between aerodynamic and structural requirements.