We present a computational study of flapping-wing aerodynamics of a calliope hummingbird (Selasphorus calliope) during fast forward flight. Three-dimensional wing kinematics were incorporated into the model by extracting time-dependent wing position from high-speed videos of the bird flying in a wind tunnel at 8.3 m s−1. The advance ratio, i.e. the ratio between flight speed and average wingtip speed, is around one. An immersed-boundary method was used to simulate flow around the wings and bird body. The result shows that both downstroke and upstroke in a wingbeat cycle produce significant thrust for the bird to overcome drag on the body, and such thrust production comes at price of negative lift induced during upstroke. This feature might be shared with bats, while being distinct from insects and other birds, including closely related swifts.
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机译：我们提出了在快进飞行过程中，圆锥形蜂鸟（Selasphorus calliope）拍打翼空气动力学的计算研究。通过从风洞中以8.3 m s -1 飞行的鸟类的高速视频中提取随时间变化的机翼位置，将三维机翼运动学纳入模型。前进比，即飞行速度与平均翼尖速度之间的比率约为1。使用浸入边界方法来模拟机翼和鸟类身体周围的流动。结果表明，在机翼节拍周期中的向下冲程和向上冲程都会对鸟类产生显着的推力，以克服对身体的阻力，而这种推力产生是以在向上冲程中引起的负升力为代价的。蝙蝠可能会共享此功能，而昆虫和其他鸟类（包括紧密相关的雨燕）则与蝙蝠不同。
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