The swimming ability of fish is greatly influenced by the hydrodynamics of their caudal fins. In this paper, the effects of flexibility and shape on the performance of a bioinspired panel are numerically studied. The flexibility is simplified as a torsional spring, and three typical shapes (i.e., square, convex, and concave shapes) are considered. The results are obtained based on three-dimensional numerical simulations of flapping panels at Re = 1000 and St = 0.5. It is shown that the flexibility can significantly affect the performance of pitching panels, by changing the phase lag between the motions of the fore and hind parts. When the phase lag is in the range of 0.1π–0.6π, the performance improvement can be obtained by the flexible panels, as compared with the rigid panel. Moreover, the maximum thrust (or efficiency) can be achieved by a flexible panel when the phase lag is approximately 0.35π (or 0.24π). On the other hand, it is found that the convex shape is optimal for thrust generation, but the square shape is optimal for propulsive efficiency. Moreover, the mechanism by which flexibility and shape can influence the performance of the pitching panel is analyzed. The results obtained here may provide some light on designing the efficient propulsor for microunderwater robots.

中文翻译：

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扭转弹簧和形状对仿生尾鳍性能的影响

鱼的游泳能力很大程度上受其尾鳍流体动力学的影响。在本文中，数值研究了柔性和形状对仿生面板性能的影响。将柔性简化为扭簧，考虑了三种典型形状（即方形、凸形和凹形）。结果是基于Re  = 1000 和St = 0.5。结果表明，通过改变前部和后部运动之间的相位滞后，灵活性可以显着影响俯仰板的性能。当相位滞后在 0.1π–0.6π 范围内时，与刚性面板相比，柔性面板可以获得性能提升。此外，当相位滞后约为 0.35π（或 0.24π）时，柔性面板可以实现最大推力（或效率）。另一方面，发现凸形最适合推力产生，但方形最适合推进效率。此外，分析了柔性和形状影响俯仰板性能的机制。这里获得的结果可能为设计用于微型水下机器人的高效推进器提供一些启示。