Clap and fling with bristled wings: effects of varying number of bristles

Tiny flying insects under 1mm in size, such as thrips, often have fringed or bristled wings. In addition, these tiny insects have been observed to use wing-wing interaction via clap and fling to augment lift generation at Reynolds number (Re) on the order of 10. Our forewing image analyses of thrips showed substantial variation in the total number of bristles, in the range of 50-120. We experimentally examined the role of number of bristles 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. The results showed that with increase in number of bristles, (a) both lift and drag force coefficients increased; (b) peak lift to peak drag ratio decreased. The effect of varying the number of bristles on leakiness will be discussed.