Study on the Effect of Flexible Passive Deformation of Tuna Caudal Fin on Swimming Performance
The high-speed and efficient swimming characteristics of tuna are valuable for designing bio-inspired underwater vehicles. Tuna use their highly deformable caudal fins as propulsors during swimming. Caudal fin deformation is categorized into skeletal-controlled active deformation and fluid-induced f...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-11-01
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| Series: | Biomimetics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2313-7673/9/11/669 |
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| Summary: | The high-speed and efficient swimming characteristics of tuna are valuable for designing bio-inspired underwater vehicles. Tuna use their highly deformable caudal fins as propulsors during swimming. Caudal fin deformation is categorized into skeletal-controlled active deformation and fluid-induced flexible passive deformation. To investigate how flexible passive deformation affects propulsion performance, simulations of four caudal fins with varying flexibilities under two <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mi>t</mi></mrow></semantics></math></inline-formula> numbers in a uniform flow are conducted using the finite volume method. This study finds that the medium-flexibility caudal fin achieves a higher time-averaged thrust coefficient without sacrificing efficiency under both high and low <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mi>t</mi></mrow></semantics></math></inline-formula> numbers. At a high <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mi>t</mi></mrow></semantics></math></inline-formula> number, the medium-flexibility caudal fin enhances thrust by reducing detrimental secondary flows. At a low <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mi>t</mi></mrow></semantics></math></inline-formula> number, the medium-flexibility caudal fin increases thrust by strengthening vortex rings, which induces a stronger backward jet. |
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| ISSN: | 2313-7673 |