Hydrodynamic considerations for multiple fin interactions in rapid maneuvers

任何生物跳跃都需要爆发力和肌肉协调能力。水中的水-空气跳水者必须产生足够的推力，以弥补流体密度的急剧下降，从而在离开水时产生力的能力。跳跃代表在有限的空间（一个身体长度）内，以有限的持续时间（直到身体离开水）进行短暂的突发动作。本研究将研究射水鱼在短距离、密闭空间、快速跳跃和游动过程中的多鳍相互作用。箭鱼是一种独特的鱼类，它使用多个鳍一起从静止的瞄准位置迅速跳出水面。在受控的实验室环境中对跳跃行为进行分析，并与水中动作进行比较，可以对一系列快速游泳行为的多鳍相互作用产生有价值的流体动力学见解。协调的鳍运动被认为是提高推力，增加稳定性和帮助瞄准在快速机动。了解复杂的多鳍游泳策略可以帮助设计仿生游泳机器人？其中多个鳍可以用来增加车辆在狭窄空间的机动性或允许控制水出口机动。本文确定的协同多推进器关系可能是未来仿生水生和空中-水生交通工具设计的范式转换。我们将考虑几个关键假设：(1)射鱼跳跃时的尾部运动学根据特定的跳跃高度进行调整；(2)在快速机动过程中，副鳍显著提高了跳跃推力和机体稳定性；(3)在竞争环境中，跳跃是一种能量可行的猎物捕获策略。鳍运动和流体流动的高速成像将用于开发跳跃过程中推力产生与动物最大跳跃高度之间关系的流体动力学模型，这是实验室中一个可控的性能变量。合成孔径粒子成像测速技术是一种流场测速的三维定量成像技术，它可以测量近体速度场。箭鱼是一种研究的模型鱼类，因为它们使用多个鳍在跳跃开始时迅速跳出水面，没有任何向上的速度。箭鱼跳跃让我们看到了鱼产生的推进力和动量，以及流体动力学的能量学。具体来说，达到最终跳高所需的动能（即势能）是多少？为了更好地理解尚未开发的海空出口模式。射箭鱼独特的形态，在尾鳍前面有更大的尾鳍（背鳍和肛鳍），潜在地增加了整体推进效率和推力产生。为了进一步了解多鳍尾迹相互作用在快速和非定常游泳行为中的总体作用，可以比较跳跃动作和水中动作。快速爆发跳跃过程中鱼鳍相互作用的表征有助于生物和进化生物学界更好地理解鱼类游动中的多鳍功能。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；这些活动可以扩展和移植到更大的K-12 STEM社区。该项目的结果将在同行评议的期刊和流体动力学和生物学界的会议上传播。

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.