Virtual manipulation of tail postures of a gliding barn owl (Tyto alba) demonstrates drag minimisation when gliding

Song, Jialei; Cheney, Jorn; Bomphrey, Richard; Usherwood, James

Abstract

Aerodynamic functions of the avian tail have been studied previously using observations of bird flight, physical models in wind tunnels, theoretical modelling, and flow visualization. However, none of these approaches has provided rigorous, quantitative evidence concerning tail functions since: appropriate manipulation and controls cannot be achieved using live animals; and the aerodynamic interplay between the wings and body challenges reductive theoretical or physical modelling approaches. Here, we have developed a comprehensive analytical drag model, calibrated by high-fidelity computational fluid dynamics (CFD), and used it to investigate the aerodynamic action of the tail by virtually manipulating its posture. The bird geometry used for CFD was reconstructed previously using stereo photogrammetry of a freely gliding barn owl (Tyto alba) and we validated the CFD simulations against wake measurements. Using this CFD-calibrated drag model, we predicted the drag production for 16 gliding flights with a range of tail postures. These observed postures are set in the context of a wider parameter sweep of theoretical postures, where the tail spread and elevation angles were manipulated independently. The observed postures of our gliding bird corresponded to near minimal total drag.

Citation

Song, J., Cheney, J., Bomphrey, R., & Usherwood, J. (2023). Virtual manipulation of tail postures of a gliding barn owl (Tyto alba) demonstrates drag minimisation when gliding. Journal of the Royal Society, Interface, https://doi.org/10.1098/rsif.2021.0710

• Journal Article Type: Article
• Acceptance Date: Jan 4, 2022
• Online Publication Date: Jan 14, 2022
• Publication Date: Feb 9, 2023
• Deposit Date: Jan 14, 2022
• Publicly Available Date: Jan 4, 2023
• Journal: Journal of the Royal Society, Interface
• Print ISSN: 1742-5689
• Electronic ISSN: 1742-5662
• Publisher: The Royal Society
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1098/rsif.2021.0710
• Keywords: tail function, drag reduction, efficiency, bird flight
• Public URL: https://rvc-repository.worktribe.com/output/1556466
• Additional Information: Research area: Animal locomotion ?; Research centre/group: Structure & Motion Lab ?; ; This work doesn't fit into any of the available options.