Fine-tuning near-boundary swimming equilibria using asymmetric kinematics
Fine-tuning near-boundary swimming equilibria using asymmetric kinematics
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DOI：
10.1088/1748-3190/aca131
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发表时间：
2022-11
影响因子：
3.4
通讯作者：
Leo Liu;Q. Zhong;Tianjun Han;K. Moored;D. Quinn
中科院分区：
文献类型：
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作者：
Leo Liu;Q. Zhong;Tianjun Han;K. Moored;D. Quinn
当在固体平面边界附近游泳时，仿生推进器可以自然地平衡到距离该边界一定距离。这些平衡如何受到不对称游泳运动学的影响是未知的。本文基于水槽实验和势流模拟，对近边界纵摇翼型进行了研究。我们发现，不对称的俯仰运动影响近边界的平衡，导致平衡移动或接近或远离平面边界。移位的幅度取决于俯仰运动学是否具有空间不对称性（例如，偏角θ 0）或时间不对称性（例如，行程速度比τ）。在稳定的平衡状态下游泳需要较少的主动控制，而将平衡状态移近边界可以产生更高的推力，而推进效率没有可测量的变化。我们的工作揭示了如何不对称运动学可以用来微调水翼与附近边界的相互作用，它提供了一个起点，了解鱼类和鸟类如何使用不对称游泳附近的基板，水面和侧壁。
When swimming near a solid planar boundary, bio-inspired propulsors can naturally equilibrate to certain distances from that boundary. How these equilibria are affected by asymmetric swimming kinematics is unknown. We present here a study of near-boundary pitching hydrofoils based on water channel experiments and potential flow simulations. We found that asymmetric pitch kinematics do affect near-boundary equilibria, resulting in the equilibria shifting either closer to or away from the planar boundary. The magnitude of the shift depends on whether the pitch kinematics have spatial asymmetry (e.g. a bias angle, θ 0) or temporal asymmetry (e.g. a stroke-speed ratio, τ). Swimming at stable equilibrium requires less active control, while shifting the equilibrium closer to the boundary can result in higher thrust with no measurable change in propulsive efficiency. Our work reveals how asymmetric kinematics could be used to fine-tune a hydrofoil’s interaction with a nearby boundary, and it offers a starting point for understanding how fish and birds use asymmetries to swim near substrates, water surfaces, and sidewalls.