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.2013 Oct 30;280(1773):20132391.
doi: 10.1098/rspb.2013.2391. Print 2013 Dec 22.

Structure of the vortex wake in hovering Anna's hummingbirds (Calypte anna)

Affiliations

Structure of the vortex wake in hovering Anna's hummingbirds (Calypte anna)

M Wolf et al. Proc Biol Sci..

Abstract

Hummingbirds are specialized hoverers for which the vortex wake has been described as a series of single vortex rings shed primarily during the downstroke. Recent findings in bats and birds, as well as in a recent study on Anna's hummingbirds, suggest that each wing may shed a discrete vortex ring, yielding a bilaterally paired wake. Here, we describe the presence of two discrete rings in the wake of hovering Anna's hummingbirds, and also infer force production through a wingbeat with contributions to weight support. Using flow visualization, we found separate vortices at the tip and root of each wing, with 15% stronger circulation at the wingtip than at the root during the downstroke. The upstroke wake is more complex, with near-continuous shedding of vorticity, and circulation of approximately equal magnitude at tip and root. Force estimates suggest that the downstroke contributes 66% of required weight support, whereas the upstroke generates 35%. We also identified a secondary vortex structure yielding 8-26% of weight support. Lift production in Anna's hummingbirds is more evenly distributed between the stroke phases than previously estimated for Rufous hummingbirds, in accordance with the generally symmetric down- and upstrokes that characterize hovering in these birds.

Keywords: aerodynamics; flight; hovering; hummingbird; lift; vortex wake.

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Figures

Figure 1.
Figure 1.
Experimental arrangement for PIV with hummingbird hovering at a feeder inside the cube. Laser planes used for PIV were (i) parasagittal and (ii) transverse. (Online version in colour.)
Figure 2.
Figure 2.
Representative wingtip movement kinematic for a hovering hummingbird, as seen from the side (a) and the top (b). Axes in millimetres.
Figure 3.
Figure 3.
Sample images of hummingbird wake at the end of the upstroke for the (i) parasagittal and (ii) transverse planes. (a) Start vortex (1) and stop vortex (2) of the downstroke; LEVD, the leading-edge vortex shed at the end of downstroke; LEV2, the leading-edge vortex of the next downstroke and the start vortex for the upstroke (3). LEV refers here to the secondary vorticity tentatively identified as a leading-edge vortex from the wing (see text for details). (b) Tip vortex (4) and root vortex (5) for the downstroke, tip circulation (6) and root circulation (7,8) for the upstroke. The silhouette of the bird is included for clarity. Colour bar indicates vorticity (s−1).
Figure 4.
Figure 4.
(a) Strength of the different vortices measured as the percentage of the required weight support calculated using downstroke stop vortex, upstroke start vortex and LEVD (secondary vorticity tentatively identified as leading-edge vortex, see text for details) as measured in the parasagittal plane, and wingtip vortex at downstroke and wingtip vorticity during the upstroke, as measured in the transversal plane. (b) Normalized circulation (Γ/Uc) for the wingtip and wing root vortices of the two stroke phases, whereU is the average wingtip velocity. Values are means ± s.e. (n = 4).
See this image and copyright information in PMC

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References

    1. Spedding GR, Hedenström AH, Rosén M. 2003. A family of vortex wakes generated by a thrush nightingale in free flight in a wind tunnel over its entire natural range of flight speeds. J. Exp. Biol. 2076, 2313–2344 (doi:10.1242/jeb.00423) - DOI - PubMed
    1. Warrick DR, Tobalske BW, Powers DR. 2005. Aerodynamics of the hovering hummingbird. Nature 435, 1094–1098 (doi:10.1038/nature03647) - DOI - PubMed
    1. Henningsson P, Spedding GR, Hedenström A. 2008. Vortex wake and flight kinematics of a swift in cruising flight in a wind tunnel. J. Exp. Biol. 211, 717–730 (doi:10.1242/jeb.012146) - DOI - PubMed
    1. Johansson LC, Wolf M, von Busse R, Winter Y, Spedding GR, Hedenström A. 2008. The near and far wake of Pallas’ long tongued bat (Glossophaga soricina). J. Exp. Biol. 211, 2909–2918 (doi:10.1242/jeb.018192) - DOI - PubMed
    1. Tobalske BW, Warrick DR, Clark CJ, Powers DR, Hedrick TL, Hyder GA, Biewener A. 2007. Three-dimensional kinematics of hummingbird flight. J. Exp. Biol. 210, 2368–2382 (doi:10.1242/jeb.005686) - DOI - PubMed

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