Robotic device shows lack of momentum enhancement for gymnotiform swimmers
Robotic device shows lack of momentum enhancement for gymnotiform swimmers
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DOI：
10.1088/1748-3190/aaf983
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发表时间：
2019-03-01
影响因子：
3.4
通讯作者：
Curet, Oscar M.
中科院分区：
文献类型：
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作者：
English, Ian;Liu, Hanlin;Curet, Oscar M.
许多鱼在保持身体伸直的同时，通过波动一条或多条细长的鳍来产生推力。这种推进机制由于其在低速时的机动性和效率，引起了人们对生物和仿生海洋推进的兴趣。分析研究发现，与没有身体的鳍相比，附着在刚性扁平身体上的鳍可以产生更大的推力，对于自然游泳运动员来说是三到四倍。然而，这种动量增强还没有得到实验证实。在这项工作中，使用了一个高度可调的机器人带状鳍模型来测试回旋游泳者的动量增强，其中波动的鳍沿着身体的腹侧运行。在一系列实验中，测量了机器人装置产生的力随机器人的身高、摆动的鳍频率和流速的变化而变化。研究发现，带状尾翼产生的推力不受物体存在的影响，因此不会因尾翼与尾翼的相互作用而产生动量增强。这些结果表明，如果鱼在特定的鳍体高比下有好处，动量增强不是原因。这一结果对理解波动鳍推进和水下航行器设计的进化适应具有更广泛的意义。
Many fish generate thrust by undulating one or multiple elongated fins while keeping their body straight. This propulsion mechanism has stimulated interest in both biology and bio- inspired marine propulsion because its maneuverability and efficiency at low speed. Analytical studies have found that a fin attached to a rigid flat body can produce substantially higher thrust compared to a fin without a body, three- to four-fold for natural swimmers. However, this momentum enhancement has not been confirmed experimentally. In this work, a robotic ribbon fin model with an adjustable-height body was used to test the momentum enhancement for gymontiform swimmers where the undulating fin runs along the ventral side of the body. In a series of experiments, the force generated by the robotic device was measured as the body height of the robot, the undulating fin frequency and the flow speed were changed. It was found that the thrust generated by the ribbon fin is not affected by the presence of a body, thereby resulting in no momentum enhancement due to the fin-body interaction. These results suggest that if there is a benefit at a specific fin-body height ratio of the fishes, the momentum enhancement is not the reason. This result has broader implications in understanding the evolutionary adaption of undulatory fin propulsion and underwater vehicles designs.