Advances in aero-acoustics of flying beetles

An understanding of the acoustics of invasive species of beetles is needed for potential detection and tracking methods in agricultural monitoring. However, the underlying mechanisms of sound generation are not well understood, especially with respect to the higher harmonic sounds. The Coconut Rhinoceros Beetle (Oryctes rhinoceros) and the Oriental Flower Beetle (Protaetia orientalis) have been studied during tethered flight with synchronized microphone array measurements and high speed video (1000–10,000 fps). The larger Coconut Rhinoceros Beetles have fundamental ∼50 Hz with distinctive torsional wing rotation compared to Oriental Flower Beetle (∼100 Hz). Computational fluid dynamics simulations were performed using the unsteady compressible flow solver (CAESIM, Adaptive Research, Inc.) using a highresolution (TVD) methodology. Models of the wing flapping motion were accomplished using mesh deformation techniques with the flapping following from rotation with prescribed bending and coupled rotation and translation from the wing’s hinge position. Fluid structure interactions with respect to the wing’s flexibility are investigated in terms of the wing bending and the leading edge vortex formation.