A STUDY OF THE AERODYNAMIC PERFORMANCE OF WEIS-FOGH WINGS (UNSTEADY FLOW, BIOFLUIDDYNAMICS, INSECT FLIGHT)

A general theory of aerodynamics, developed on the basis of viscous flow equations, is utilized in an investigation of the Weis-Fogh problem. The general theory is ideally-suited for non-linear unsteady aerodynamic problems. It is also shown that this general theory permits the important flow elements dominating the aerodynamics of non-linear unsteady flows to be identified and their contributions evaluated individually.; The Weis-Fogh problem is a well-known biofluiddynamics problem involving articulate lifting bodies. The present study has yielded useful results for the lift and drag acting on a wing undergoing the fling and the clap phases of the Weis-Fogh motion. Closed form expressions have been obtained for the unsteady aerodynamic forces and the power expenditure of the Weis-Fogh wing. These results have led to the identification of major contributors to aerodynamic performance of the Weis-Fogh wings and to an assessment of the relative importance of these contributors.; The influence of leading-edge separation on the Weis-Fogh mechanism is investigated. The analysis employs a single vortex model. Results of the present study compare reasonably well with Maxworthy's laboratory observations at high Reynolds number. It confirms that the separation significantly enhances the circulation around each of the wings. It is also shown that the presence of the separation vortices has a substantial effect on the aerodynamic performance of the Weis-Fogh motion.