Upwash exploitation and downwash avoidance by flap phasing in ibis formation flight
Upwash exploitation and downwash avoidance by flap phasing in ibis formation flight
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DOI：
10.1038/nature12939
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发表时间：
2014-01-16
期刊：
影响因子：
64.8
通讯作者：
Usherwood, James R.
中科院分区：
文献类型：
--
作者：
Portugal, Steven J.;Hubel, Tatjana Y.;Usherwood, James R.
许多物种以高度组织化的群体旅行（1-3）。这些配置最常被引用的功能是减少能量消耗和增强集合中个体的运动性能（4-11）。鸟群独特的V形队形长期以来一直吸引着研究人员，并继续吸引科学和大众的关注（4，7，9 -14）。人们普遍认为，这种聚集通过利用前一只鸟的翅膀产生的上洗区域，为那些飞在另一只鸟后面和一侧的鸟提供了能量上的好处（4，7，9 -11），尽管对这些形成的空气动力学影响的明确解释仍然难以捉摸。在这里，我们表明，个人的北方秃朱鹭（Geronticus eremita）飞行在一个V群的位置在空气动力学的最佳位置，在他们同意理论空气动力学预测。此外，我们表明，鸟类翼尖路径的连贯性飞行时，在V位置，拍打空间的相位，从而使上洗捕获在整个皮瓣周期最大化。相比之下，当鸟飞紧跟着另一只鸟-在流向的位置-有没有翼尖路径的连贯性，翼拍是在空间反相。这可以潜在地减少下洗对后续鸟的不利影响。这些空气动力学成就以前被认为是不可能的鸟类，因为复杂的飞行动力学和感官反馈，将需要执行这样的壮举（12，14）。我们的结论是，复杂的机制参与V形编队飞行表明意识到附近的羊群队友的空间尾流结构，和显着的能力，无论是感觉或预测it. We建议，鸟类在V形编队有相位策略，以科普动态唤醒产生的扑翼。
Many species travel in highly organized groups(1-3). The most quoted function of these configurations is to reduce energy expenditure and enhance locomotor performance of individuals in the assemblage(4-11). The distinctive V formation of bird flocks has long intrigued researchers and continues to attract both scientific and popular attention(4,7,9-14). The well-held belief is that such aggregations give an energetic benefit for those birds that are flying behind and to one side of another bird through using the regions of upwash generated by the wings of the preceding bird(4,7,9-11), although a definitive account of the aerodynamic implications of these formations has remained elusive. Here we show that individuals of northern bald ibises (Geronticus eremita) flying in a V flock position themselves in aerodynamically optimum positions, in that they agree with theoretical aerodynamic predictions. Furthermore, we demonstrate that birds show wingtip path coherence when flying in V positions, flapping spatially in phase and thus enabling upwash capture to be maximized throughout the entire flap cycle. In contrast, when birds fly immediately behind another bird-in a streamwise position-there is no wingtip path coherence; the wing-beats are in spatial anti-phase. This could potentially reduce the adverse effects of downwash for the following bird. These aerodynamic accomplishments were previously not thought possible for birds because of the complex flight dynamics and sensory feedback that would be required to perform such a feat(12,14). We conclude that the intricate mechanisms involved in V formation flight indicate awareness of the spatial wake structures of nearby flock-mates, and remarkable ability either to sense or predict it. We suggest that birds in V formation have phasing strategies to cope with the dynamic wakes produced by flapping wings.