Aerodynamics of Insect Flight In TurbulentFlow

昆虫飞行的空气动力学问题目前受到高度重视。昆虫飞行的基本原理最初是在假定昆虫在静止的空气中运动的情况下探索的。然而，自然环境通常是动荡的，但我们对昆虫如何在大风天飞行知之甚少。对于人造微型飞行器来说，在困难的气流条件下飞行同样重要。本计画从实验生物学与计算流体力学的互补观点，探讨昆虫与乱流的互动。我们将定义一组具有可重复统计特性的模型湍流，系统地改变湍流运动尺度的能量含量，在实验和数值模拟中具有相似的流动条件。我们还把重点放在机翼弹性的意义，并设计一个合适的灵活的机翼模型，密切模仿的弹性特性的真实的机翼，我们在实验设备中测量。生物学实验解释了动物的整个复杂性，包括大脑、感觉系统以及在扰动飞行条件下翅膀拍打运动学的变化。数值模拟允许研究孤立的影响，从而降低问题的复杂性。我们一方面结合了联合收割机对系留和自由飞行昆虫的生物学实验，另一方面结合了具有刚性和柔性翅膀的模型昆虫在类似湍流环境中系留和自由飞行的数值模拟。这使得我们考虑的三个主要问题，至少给出部分答案：（一）环境湍流的影响，好处和限制扑翼昆虫飞行的空气动力学？(ii)紊流如何影响柔性和刚性机翼扑翼飞行的能量消耗？(iii)昆虫采用什么样的行为策略来科普湍流扰动？这些问题是相关的基础和应用研究，其跨学科的性质需要采用几个角度。

The aerodynamics of insect flight currently receives high attention. The fundamentals of insect flight were first explored assuming that insects move in quiescent air. However, natural environment is typically turbulent, but we know very little on how insects manage to fly on windy days. For man-made micro air vehicles it is likewise important to fly under difficult flow conditions. This project proposes to investigate the interaction of insects with turbulence from complementary perspectives of experimental biology and computational fluid dynamics. We will define a set of model turbulent flows with reproducible statistical properties, varying systematically the energy content of the scales of turbulent motion, with similar flow conditions in experiments and numerical simulations. We also put a major emphasis on the significance of wing elasticity, and devise a suitable flexible wing model that closely mimics the elastic properties of real wings, which we measure in an experimental facility. Biological experiments account for the whole complexity of animals, including the brain, sensory system and the resulting changes in the wing-beat kinematics under perturbed flight conditions. Numerical simulations allow studying isolated effects and thus to reduce the problem's complexity. We combine biological experiments on tethered and freely flying insects on the one hand, and numerical simulations of model insects with rigid and flexible wings in tethered and free flight in a similar turbulent flow environment on the other hand. This allows giving at least partial answers to the three major questions we consider: (i) What are impacts, benefits and limitations of environmental turbulence on the aerodynamics of flapping insect flight? (ii) How does turbulence affect the energetic cost of flapping flight with flexible and rigid wings? (iii) What behavioral strategies do insects employ to cope with turbulent perturbations? These questions are relevant for both fundamental and applied research, and their interdisciplinary nature requires employing several perspectives.