Meeting Abstract
Flight-capable miniature insects (size under 1 mm), such as thrips and fairyflies, often have wings with long bristles on the fringes. Flapping flight at such small scales is challenged by large viscous forces on the wings, characterized by Reynolds number (Re) on the order of 10 or lower. These insects use large stroke amplitudes that result in wing-wing interaction (clap and fling). Previous studies have shown that wing bristles can lower drag forces experienced during clap and fling. However, the role of the number of bristles on clap and fling aerodynamics has not been previously examined. Our forewing image analyses of about 40 species of thrips and fairyflies showed substantial variation in the total number of bristles and aspect ratio (AR) of the wing, in the range of 50-120 and 1.3-5, respectively. We experimentally examined the role of number of bristles and change in AR on force generation and leakiness of flow through the bristles. A dynamically scaled robotic model mimicking clap and fling mechanism was used to comparatively test bristled wing models with varying number of bristles at Re of 10. Non-dimensional lift and drag coefficients were estimated from strain gauge measurements of time-varying forces. The results showed that with increase in number of bristles, both lift and drag force coefficients increased. The effect of varying the number of bristles and AR on leakiness will be discussed.
