Hydrodynamic considerations for multiple fin interactions in rapid maneuvers

任何生物体的跳跃都需要高爆发力和肌肉协调。水上从水到空气的跳跃必须产生足够的推力，以应对离开水时流体密度的急剧下降，从而产生力量的能力。跳跃是指在有限的时间内(直到身体离开水)，在有限的空间内(单一身体长度)进行短暂的突击动作。这项工作将研究箭鱼在短距离、受限空间、快速跳跃和游泳动作中的多鳍相互作用。射手鱼是一种独特的鱼类，它使用多条鳍协调一致，从静止的瞄准位置快速跳出水面。在受控的实验室环境中对跳跃行为进行分析，并与水中操作进行比较，可以为一系列快速游泳行为的多鳍相互作用提供有价值的水动力学见解。协调的鳍运动被认为可以增加推力，增加稳定性，并在快速机动时帮助瞄准。了解复杂的多鳍游泳策略可以帮助设计受生物启发的游泳机器人？在狭窄的空间中，可以使用多个尾翼来增加车辆的机动性，或者允许受控的出水机动。本文确定的协同多推进器关系可能是未来生物灵感水上和空中-水上交通工具设计的范例转换。将考虑几个关键假设：(1)弓箭鱼跳跃过程中的尾部运动学针对特定的跳跃高度进行调整；(2)在快速动作中，副鳍显著增强跳跃推力和身体稳定性；(3)在竞争环境中，跳跃是一种能量上可行的猎物捕获策略。将使用鳍运动和流体流动的高速成像来开发一个流体动力学模型，用于研究跳跃过程中的推力产生和动物最大跳跃高度之间的关系，这是实验室中的一个可控性能变量。合成孔径粒子图像测速仪是一种用于流场测速的定量三维成像技术，它可以测量近体的速度场。射手鱼是一个值得研究的模范鱼类物种，因为它们使用多个鳍一起快速跳出水面，在跳跃开始时没有任何向上的速度。射手鱼的跳跃让我们能够看到鱼产生的推进力和动量，以及水动力能量学？具体地说，达到最终跳跃高度所需的动能(即势能)？以更好地理解尚未探索的海空出口模式。射手鱼的独特形态，尾鳍(背鳍和肛鳍)正好在尾尾前面，潜在地增加了整体推进效率和推力产生。跳跃运动和水中运动可以进行比较，以进一步了解多个尾流相互作用在快速和非定常游泳行为中的主导作用。快速跳跃过程中鳍-鳍相互作用的特征有助于生物界和进化生物界更好地了解多鳍在鱼类游泳中的功能。拟议的STEM外展活动通过编程和动手实验数据处理，让学生参与流体物理和生物启发设计；这些活动可扩展，并可移植到更大的K-12 STEM社区。该项目的结果将在同行评议的期刊上以及流体动力学和生物生物学社区的会议上传播。

Jumping by any organism requires high bursts of power and muscular coordination. Aquatic water-to-air jumpers must produce enough thrust to account for the drastic drop in fluid density, and thus force-producing ability, when exiting the water. Jumps represent short burst maneuvers in a restricted space (a single body length) with finite duration (until the body has exited the water). This work will investigate multi-fin interactions during short distance, confined space, rapid jumping and swimming maneuvers in archer fish. The archer fish is a unique fish species that uses multiple fins in concert to rapidly jump out of the water from a stationary aiming position. The analysis of jumping behaviors, in a controlled laboratory environment, and comparison with in-water maneuvers, can yield valuable hydrodynamic insight into multi-fin interactions for a range of rapid swimming behaviors. Coordinated fin motions are thought to enhance thrust, increase stability and aid in aiming during rapid maneuvers. Understanding complex multi-fin swimming strategies can help inform bio-inspired swimming robot designs ? where multiple fins could be employed to increase vehicle maneuverability in tight spaces or allow for controlled water-exit maneuvers. Synergistic multi-propulsor relationships identified herein could be paradigm-shifting for the design of future bioinspired aquatic and aerial-aquatic vehicles. Several key hypotheses will be considered: (1) tail kinematics during archer fish jumping are tuned for specific jump heights; (2) secondary fins significantly enhance jump thrust and body stability during rapid maneuvers; (3) jumping is an energetically viable prey capture strategy in competitive environments. High-speed imaging of fin motions and fluid flows will be used to develop a hydrodynamic model for the relationship between thrust production during a jump and maximum animal jump height, which is a controllable performance variable in the laboratory. Synthetic aperture particle image velocimetry, a quantitative three-dimensional imaging technique for flow field velocimetry, will measure the near body velocity fields. Archer fish are a model fish species to investigate, as they use multiple fins in concert to rapidly jump out of the water without any upwards velocity at jump initiation. The archer fish jump allows us to look at propulsive forces and momentum generated by the fish, as well as the hydrodynamic energetics ? specifically the kinetic energy required to reach the final jump height (i.e. potential energy) ? to better understand the unexplored paradigm of sea-to-air exit. The unique morphology of the archer fish, with larger aft fins (dorsal and anal fins) just in front of the caudal tail, potentially adds both to the overall propulsive efficiency and thrust production. Jump maneuvers and in-water maneuvers can be compared for further understanding of the overarching role of multiple fin wake interactions in rapid and unsteady swimming behaviors. The characterization of fin-fin interactions during rapid burst jumping helps the organismal and evolutionary biology communities better understand multi-fin function in fish swimming. The proposed STEM outreach activities engage students in fluid physics and bioinspired design, through programming and hands-on experimental data processing; these activities are scalable and portable to the larger K-12 STEM community. Results of the project will be disseminated in peer-reviewed journals and at conferences in both the fluid dynamic and organismal biology communities.