Interaction of the elytra and hind wings of a rhinoceros beetle (trypoxylus dichotomus) during take-off

Abstract

The elytra are a pair of hardened wings that cover the abdomen of a beetle to protect beetles hind wings. During take-off, these elytra open and flap in phase with the hind wings. We investigated the effect of the elytra flapping on the beetles aerodynamic performance. Numerical simulations are performed at Re=17,000 (based on the maximum velocity at wing tip and the mean chord length of the hind wing of a rhinoceros beetle during take-off) using an immersed boundary method. The simulations are focused on take-off, and the wing kinematics used are directly obtained from experimental observations using high speed cameras. The simulation results shows the three-dimensional vortical structures generated by the hind wing of the beetle and their interaction with the elytra. The presence of elytra has no effect on the lift generated by the hind wings, and the lift force on the elytra themselves is negligible.