The aerodynamics of tiny insect flight with bristled wings

A vast body of research has described the complexity of flight in insects ranging from the fruit fly, Drosophila melanogaster, to the hawk moth, Manduca sexta. Over this range of scales, flight aerodynamics as well as the relative lift and drag forces generated are surprisingly similar. The smallest flying insects have received far less attention, although previous work has shown that flight kinematics and aerodynamics can be significantly different. Furthermore, the smallest of the flying insects are often characterized by a bristled wing form. In this presentation, we have used a three-pronged approach that consists of measurements of flight kinematics in the tiny insect Thysanoptera (thrips), measurements of flow velocities using physical models, and direct numerical simulations to compute lift and drag forces. From high speed videos, we find that thrips use clap and fling during flight and occasionally stop flapping and apparently parachute. Using physical models and CFD, we find that drag forces generating during clap and fling with solid wings can be an order of magnitude larger than lift forces. If the wings are modeled as a porous layer to take into account the bristled wing form, drag forces can be significantly reduced while lift forces are maintained.