Data from: Smart wing rotation and trailing-edge vortices enable high frequency mosquito flight

Mosquitoes exhibit unusual 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 group1. This shifts weight support away from the translation-dominated, aerodynamic mechanisms used by most insects2, 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 free-flight mosquito wing kinematics, 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, although mosquitoes use familiar separated flow patterns, much of the aerodynamic force that supports their weight is generated in a manner unlike any previously described for a flying animal. 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 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 they are therefore relatively immune to the shallow flapping amplitude. Moreover, these mechanisms are particularly well suited to high aspect ratio mosquito wings.蚊子展现出迥异于常规的翅膀运动学特性：其修长纤细的翅翼相较于自身体型，振翅频率极高（超过800赫兹），且振程幅值低于所有其他昆虫类群¹。这使得其重量支撑机制脱离了大多数昆虫²以及直升机、固定翼飞机所采用的、以平动主导的空气动力学模式，转向了人们尚未完全明晰的、在每个半振程结束时俯仰转动过程中产生的旋转力学机制。本文报道了自由飞行状态下蚊子的翅翼运动学数据，采用搭载重叠网格（overset grids）的计算流体动力学（computational fluid dynamics）方法求解完整的纳维-斯托克斯方程（Navier–Stokes equations），并通过体内流动测量对研究结果进行验证。研究表明，尽管蚊子采用了昆虫飞行中近乎普遍存在的经典分离流模式，但其支撑体重的绝大部分气动力，却是以此前从未在飞行动物中被报道过的方式生成的。其核心特性包含三点：一是前缘涡（leading-edge vortices）——这是一种在昆虫飞行中几乎无处不在的经典力学机制；二是由振程反转阶段的尾迹捕获效应引发的后缘涡；三是旋转阻力。其中两项新的气动力机制基本与翅翼运动速度无关，而是依赖于每个半振程结束时的俯仰角（翅翼转动）快速变化，因此受限于较浅的振程幅值的影响相对较弱。此外，这些气动机理特别适配蚊子翅翼的高展弦比（aspect ratio）构型。