Ear-body lift and a novel thrust generating mechanism revealed by the complex wake of brown long-eared bats (Plecotus auritus)
Autor: | Jonas Håkansson, Anders Hedenström, Lasse Hjort Jakobsen, L. Christoffer Johansson |
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Rok vydání: | 2016 |
Předmět: |
030110 physiology
0106 biological sciences 0301 basic medicine Wing root animal structures Acoustics Human echolocation Wake Models Biological 010603 evolutionary biology 01 natural sciences Article 03 medical and health sciences Chiroptera Journal Article otorhinolaryngologic diseases Animals Wings Animal Simulation Multidisciplinary Wing biology Ear biology.organism_classification Biomechanical Phenomena Vortex Lift (force) Flight Animal Wingtip vortices Plecotus auritus sense organs Rheology Geology |
Zdroj: | Johansson, L C, Håkansson, J, Jakobsen, L & Hedenström, A 2016, ' Ear-body lift and a novel thrust generating mechanism revealed by the complex wake of brown long-eared bats (Plecotus auritus) ', Scientific Reports, vol. 6, pp. 24886 . https://doi.org/10.1038/srep24886 Scientific Reports |
ISSN: | 2045-2322 |
Popis: | Large ears enhance perception of echolocation and prey generated sounds in bats. However, external ears likely impair aerodynamic performance of bats compared to birds. But large ears may generate lift on their own, mitigating the negative effects. We studied flying brown long-eared bats, using high resolution, time resolved particle image velocimetry, to determine the aerodynamics of flying with large ears. We show that the ears and body generate lift at medium to cruising speeds (3–5 m/s), but at the cost of an interaction with the wing root vortices, likely reducing inner wing performance. We also propose that the bats use a novel wing pitch mechanism at the end of the upstroke generating thrust at low speeds, which should provide effective pitch and yaw control. In addition, the wing tip vortices show a distinct spiraling pattern. The tip vortex of the previous wingbeat remains into the next wingbeat and rotates together with a newly formed tip vortex. Several smaller vortices, related to changes in circulation around the wing also spiral the tip vortex. Our results thus show a new level of complexity in bat wakes and suggest large eared bats are less aerodynamically limited than previous wake studies have suggested. |
Databáze: | OpenAIRE |
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