Hawkmoth flight in the unsteady wakes of flowers
Hawkmoth flight in the unsteady wakes of flowers
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DOI：
10.1242/jeb.179259
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发表时间：
2018-02
影响因子：
2.8
通讯作者：
Megan Matthews;S. Sponberg
中科院分区：
文献类型：
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作者：
Megan Matthews;S. Sponberg
飞行动物在阵风和花尾流产生不稳定流的环境中机动和盘旋。虽然飞行机动和空气动力学机制都已被独立研究过，但在流动已经不稳定的环境中，它们如何相互作用的问题却知之甚少。飞蛾在花后盘旋觅食。我们研究了天蛾在风洞中跟踪3D打印机器人花的情况。我们可视化的流在尾流和周围的翅膀，并比较跟踪性能与以前的实验在静止空气飞行室。就像在静止的空气中一样，飞蛾在花尾流中飞行，在自然花朵运动的低频下表现出近乎完美的跟踪。然而，在花尾流中的跟踪导致在2和5Hz之间的较大过冲。花跟踪的系统识别表明，飞蛾也显示降阶动力学在风中相比，静止的空气。花尾流的烟雾可视化显示，占主导地位的旋涡脱落对应于相同的频带，增加的过冲。尽管这些大的影响跟踪动态风，前缘涡（LEV）保持绑定到机翼在整个翼行程，并没有爆裂。LEV也保持了稳定空气中看到的相同的定性结构。在减少的花跟踪期间，稳定的LEV的持久性证明了悬停和机动之间的相互作用。突出显示的文章：飞蛾在花朵后面机动，显示出简化的花朵跟踪动态。在花尾流中，前缘涡不会破裂，而是连续地延伸穿过机翼和胸部。
ABSTRACT Flying animals maneuver and hover through environments where wind gusts and flower wakes produce unsteady flow. Although both flight maneuvers and aerodynamic mechanisms have been studied independently, little is known about how these interact in an environment where flow is already unsteady. Moths forage from flowers by hovering in the flower's wake. We investigated hawkmoths tracking a 3D-printed robotic flower in a wind tunnel. We visualized the flow in the wake and around the wings and compared tracking performance with previous experiments in a still-air flight chamber. As in still air, moths flying in the flower wake exhibit near-perfect tracking at the low frequencies at which natural flowers move. However, tracking in the flower wake results in a larger overshoot between 2 and 5 Hz. System identification of flower tracking reveals that moths also display reduced-order dynamics in wind compared with still air. Smoke visualization of the flower wake shows that the dominant vortex shedding corresponds to the same frequency band as the increased overshoot. Despite these large effects on tracking dynamics in wind, the leading edge vortex (LEV) remains bound to the wing throughout the wingstroke and does not burst. The LEV also maintains the same qualitative structure seen in steady air. Persistence of a stable LEV during decreased flower tracking demonstrates the interplay between hovering and maneuvering. Highlighted Article: Moths maneuvering in the wake of flowers display simplified flower tracking dynamics. In the flower wake, the leading edge vortex does not burst and extends continuously across the wings and thorax.