Smart wing rotation and trailing-edge vortices enable high frequency mosquito flight.
Smart wing rotation and trailing-edge vortices enable high frequency mosquito flight.
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DOI：
10.1038/nature21727
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发表时间：
2017-04-06
期刊：
影响因子：
64.8
通讯作者：
Walker SM
中科院分区：
文献类型：
--
作者：
Bomphrey RJ;Nakata T;Phillips N;Walker SM
蚊子表现出独特的翅膀运动学;它们长而细长的翅膀以相对于它们的大小而言非常高的频率（>800 Hz）拍打，并且比任何其他昆虫群体具有更低的冲程幅度。这将重量支撑从大多数昆虫以及直升机和飞机所使用的以飞行为主的空气动力学机制转移到在每个半冲程结束时俯仰时发生的知之甚少的旋转机制。在这里，我们报告机翼运动学和解决全纳维尔-斯托克斯方程使用计算流体动力学与重叠网格和验证我们的结果与体内流动测量。我们表明，虽然熟悉的分离流动模式是由蚊子，大部分的空气动力，支持他们的重量产生的方式不同于任何以前描述的飞行动物。总的来说，有三个关键特征：前缘涡（一个众所周知的机制，似乎是几乎无处不在的昆虫飞行），后缘涡所造成的一种新形式的唤醒捕捉在中风逆转，和旋转阻力。这两个新元素在很大程度上独立于机翼速度，而是依赖于每个半行程结束时俯仰角（机翼旋转）的快速变化，因此相对不受浅扑动幅度的影响。此外，这些机构特别适合于高纵横比的蚊子翅膀。
Mosquitoes exhibit unique wing kinematics; their long, slender wings flap at remarkably high frequencies for their size (>800 Hz) and with lower stroke amplitudes than any other insect group. This shifts weight support away from the translation-dominated, aerodynamic mechanisms used by most insects, as well as by helicopters and aeroplanes, towards poorly understood rotational mechanisms that occur when pitching at the end of each half-stroke. Here we report wing kinematics and solve the full Navier-Stokes equations using computational fluid dynamics with overset grids and validate our results with in vivo flow measurements. We show that, while familiar separated flow patterns are used by mosquitoes, much of the aerodynamic force that supports their weight is generated in a manner unlike any previously described flying animal. In total, there are three key features: leading-edge vortices (a well-known mechanism that appears to be almost ubiquitous in insect flight), trailing-edge vortices caused by a novel form of wake capture at stroke reversal, and rotational drag. The two new elements are largely independent of the wing velocity, instead relying on rapid changes in the pitch angle (wing rotation) at the end of each half stroke, and are therefore relatively immune to the shallow flapping amplitude. Moreover, these mechanisms are particularly well-suited to high-aspect ratio mosquito wings.