Department of Mechanical Engineering , Vanderbilt University , Nashville, TN 37235, USA.
Field Research Station at Fort Missoula, Division of Biological Sciences , University of Montana , Missoula, MT 59812, USA.
R Soc Open Sci. 2016 Jun 8;3(6):160230. doi: 10.1098/rsos.160230. eCollection 2016 Jun.
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.
我们对西美冠蓝鸦（Selasphorus calliope）在高速前飞过程中的拍动翼空气动力学进行了计算研究。通过从在 8.3 m/s 的风速下在风洞中飞行的鸟的高速视频中提取随时间变化的翼位置，将三维翼运动学纳入模型中。前向比，即飞行速度与平均翼尖速度的比值约为 1。使用浸没边界方法来模拟翅膀和鸟体周围的流动。结果表明，在一个拍动周期中，无论是下拍还是上拍，都能产生显著的推力，以克服对鸟体的阻力，而这种推力的产生是以在上拍过程中产生负升力为代价的。这一特征可能与蝙蝠共有，而与昆虫和其他鸟类（包括亲缘关系密切的雨燕）不同。
