Meeting Abstract

15.4  Sunday, Jan. 4  Diving wasps: swimming and flying at very low Reynolds numbers MILLER, LA*; SANTHANAKRISHNAN, A; University of North Carolina at Chapel Hill lam9@email.unc.edu

The family Mymaridae (fairyflies) is comprised of tiny parasitoid wasps that include the smallest of all insects. The females of several species in this family are known to dive into the water and swim with their wings and hind legs in order to parasitize the eggs of larger insects. Fairyflies also represent some of the smallest organisms that use flapping appendages to generate lift and thrust, in both swimming and flying. The forewings of the insect have reduced venation and a marginal fringe of hairs. The hind wings are extremely narrow and contain setae along the entire margin. In this study, we used computational fluid dynamics and particle image velocimetry (PIV) to characterize the flow around simplified models of fairyfly flapping wings and hind legs. We described the net thrust in water and lift in air produced over a range of Reynolds numbers and relate the magnitude of these forces to the behavior of the wake behind the flapping appendages. The assumption that the fringed wings act as solid plates in both air and water was also examined. At these scales, both swimming and flying become relatively inefficient, and these insects are likely pushing the lower limits of locomotion with flapping appendages.