Mechanism and scaling of wing tone generation in mosquitoes

The generation of sound from flapping (i.e. wing tones) of mosquito (Culex) wings is investigated using computational modeling. The flow field around the wing is simulated by solving the incompressible Navier-Stokes equations using a sharp-interface immersed boundary method, and the aeroacoustic sound is predicted by the Ffowcs Williams and Hawkings equation using data from the aerodynamic simulations. In addition to the aerodynamics, the characteristics of mosquito's wing tone, spectral directivity patterns, and generation mechanisms are investigated. The effects of wing-beat frequency and stroke amplitude are also studied, and scaling analysis for the mean lift, mechanical power, and overall wing tone sound power are performed to understand the effects of the wing shape and kinematics parameters. The analysis shows that the high wing aspect-ratio, high wing beat frequency, and small stroke amplitude adopted by mosquitoes enable efficient generation of high-intensity wing-tones for acoustic communications. The present findings may also apply to the optimized noise control in the flapping-wing micro air vehicles (FWMAV).