- Featured in Physics
- Editors' Suggestion
- Access by Xinjiang University
Effect of wing sweep on a perching maneuver
Phys. Rev. Fluids 7, 044702 – Published 15 April, 2022
DOI: https://doi.org/10.1103/PhysRevFluids.7.044702
Abstract
While landing, birds often perform a perching maneuver, which involves pitching their wings upward while decelerating to a complete stop. This study is motivated by the observation that some birds fold their wings to create a wing sweep during such perching. The objective of this study is to find out whether such a wing sweep helps during a perching maneuver. We use two flat plates, one with a sweep and another without any sweep, and consider a deceleration maneuver where both of them decelerate to stop from Reynolds number . We consider two cases: one, where the wings undergo only heaving, and two, where the wings perform both heaving and pitching. The latter maneuver was designed to mimic perching. By performing experiments and simulations, we compare the temporal evolution of the instantaneous forces and the vortex dynamics of both these plates. We show that during a major part of the deceleration, the instantaneous lift forces are higher in the case of the plate with sweep compared to the plate with no sweep during both kinematics. Our results indicate that the higher lift in the swept plate case was contributed by a stable leading-edge-vortex (LEV) which remains attached to the plate. This increase in stability was contributed by the spanwise vorticity convection caused by a distinct spanwise flow on the swept plate, as revealed by the numerical simulation. We also show that combined pitching and heaving resulted in higher force peaks, and the forces also decayed at a faster rate in this case compared to the heave-only case. Finally, by using an analytical model for unsteady flows, we prove that the higher lift characteristics of the swept plate were entirely due to higher circulatory forces.
Physics Subject Headings (PhySH)
synopsis
The Aerodynamics of Perching Birds
Experiments and simulations suggest that the airplane-like wing position adopted by some birds when they land helps to increase lift.
See more in Physics
Article Text
References (28)
- A. C. Carruthers, A. L. R. Thomas, and G. K. Taylor, Automatic aeroelastic devices in the wings of a steppe eagle Aquila nipalensis, J. Expl Biol. 210, 4136 (2007).
- D. T. Polet, D. E. Rival, and G. D. Weymouth, Unsteady dynamics of rapid perching manoeuvres, J. Fluid Mech. 767, 323 (2015).
- G. D. Weymouth and M. S. Triantafyllou, Global vorticity shedding for a shrinking cylinder, J. Fluid Mech. 702, 470 (2012).
- G. D. Weymouth and M. S. Triantafyllou, Ultra-fast escape of a deformable jet-propelled body, J. Fluid Mech. 721, 367 (2013).
- C. Hartloper and D. E. Rival, Vortex development on pitching plates with lunate and truncate planforms, J. Fluid Mech. 732, 332 (2013).
- K. Granlund, M. Ol, and L. Bernal, eds., Experiments on Pitching Plates: Force and Flowfield Measurements at Low Reynolds Numbers (AIAA SciTech, Orlando, FL, 2011).
- T. O. Yilmaz and D. Rockwell, Flow structure on finite-span wings due to pitch-up motion, J. Fluid Mech. 691, 518 (2012).
- A. M. Berg and A. A. Biewener, Wing and body kinematics of takeoff and landing flight in the pigeon (Columba livia), J. Expl Biol. 213, 1651 (2010).
- P. Provini, B. W. Tobalske, K. E. Crandell, and A. Abourachid, Transition from wing to leg forces during landing in birds, J. Expl Biol. 217, 2659 (2014).
- K. O. Granlund, M. V. Ol, and L. P. Bernal, Unsteady pitching flat plates, J. Fluid Mech. 733, R5 (2013).
- D. Rival, T. Prangemeier, and C. Tropea, The influence of airfoil kinematics on the formation of leading-edge vortices in bio-inspired flight, Exp. Fluids 46, 823 (2009).
- Y. S. Baik, L. P. Bernal, K. Granlund, and M. V. Ol, Unsteady force generation and vortex dynamics of pitching and plunging aerofoils, J. Fluid Mech. 709, 37 (2012).
- M. R. Visbal and J. S. Shang, Investigation of the flow structure around a rapidly pitching airfoil, AIAA J. 27, 1044 (1989).
- T. Maxworthy, The formation and maintenance of a leading-edge vortex during the forward motion of an animal wing, J. Fluid Mech. 587, 471 (2007).
- R. Blake, The energetics of hovering in the mandarin fish (Synchropus picturatus), J. Exp. Biol. 82, 25 (1979).
- P. W. Webb, The effect of solid and porous channel walls on steady swimming of steelhead trout Oncorhynchus mykiss, J. Exp. Biol. 178, 97 (1993).
- F. R. Hainsworth, Induced drag savings from ground effect and formation flight in brown pelicans, J. Exp. Biol. 135, 431 (1988).
- J. M. Rayner, On the aerodynamics of animal flight in ground effect, Philos. Trans. R. Soc. B 334, 119 (1991).
- J. M. Rayner and A. L. Thomas, On the vortex wake of an animal flying in a confined volume, Philos. Trans. R. Soc. B 334, 107 (1991).
- R. V. Baudinette and K. Schmidt-Nielsen, Energy cost of gliding flight in herring gulls, Nature (London) 248, 83 (1974).
- J. H. J. Buchholz and A. J. Smits, The wake structure and the thrust performance of a rigid low-aspect-ratio pitching panel, J. Fluid Mech. 603, 331 (2008).
- E. Blevins and G. V. Lauder, Swimming near the substrate: A simple robotic model of stingrey locomotion, Bioinspir. Biomim. 8, 016005 (2013).
- K. V. Rozhdestvensky, Wing-in-ground effect vehicles, Prog. Aerosp. Sci. 42, 211 (2006).
- J. B. Barlow, W. H. B. Rae, W. H. Rae, and A. Pope, Low-Speed Wind-Tunnel Testing, 3rd ed. (Wiley, New York, NY, 1999).
- L. Graftieaux, M. Michard, and N. Grosjean, Combining piv, pod and vortex identification algorithms for the study of unsteady turbulent swirling flows, Meas. Sci. Technol. 12, 1422 (2001).
- STAR CCM+ Users Manual (2018).
- H. Babinsky, P. R. R. J. Stevens, A. R. Jones, L. P. Bernal, and M. V. Ol, eds., Low Order Modelling of Lift forces for Unsteady Pitching and Surging Wings (AIAA SciTech, San Diego, CA, 2016).
- Z. Y. Li, L. H. Feng, J. Kissing, C. Tropea, and J. J. Wang, Experimental investigation on the leading-edge vortex formation and detachment mechanism of a pitching and plunging plate, J. Fluid Mech. 901, A17 (2020).
