Comparative Investigations on Active and Passive Tails of Undulating Swimmers

Fuente: arXiv
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Auteurs principaux: Nayak, Dev Pradeepkumar, Tarokh, Ali, Khalid, Muhammad Saif Ullah
Format: Preprint
Publié: 2025
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author Nayak, Dev Pradeepkumar
Tarokh, Ali
Khalid, Muhammad Saif Ullah
author_facet Nayak, Dev Pradeepkumar
Tarokh, Ali
Khalid, Muhammad Saif Ullah
contents Fish display remarkable swimming capabilities through the coordinated interaction of the body and caudal fin, yet the potential role of a passively pitching tail in enhancing hydrodynamic performance remains unresolved. In this work, we evaluate the performance of a carangiform swimmer equipped with either an actively pitching tail or a passively pitching tail. Fluid-structure interactions-based simulations are employed to asses how variations in joint stiffness, damping, and inertia influence thrust generation, power demand, and overall stability at two representative Reynolds numbers of 500 and 5000. The results reveal that actively pitching tails tend to generate greater thrust, while passively pitching tails deliver improved outcomes in terms of the power demand at the lower Reynolds number. Larger pitching amplitudes contribute positively only when associated with higher swimming frequency, when produced by reduced inertia for more flexible joints, they lead to unfavorable effects. At the higher Reynolds number, active tails consistently outperform passive ones, although a small subset of passive cases still achieve favorable performance. Across all cases, a recurring balance emerges, with thrust production and power expenditure varying inversely. These findings clarify the hydrodynamic consequences of passive versus active tail motion and establish design principles for bio-inspired underwater vehicles, where smaller swimmers may benefit from passive tail pitching, while larger swimmers are better served by active control
format Preprint
id arxiv_https___arxiv_org_abs_2511_03057
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Comparative Investigations on Active and Passive Tails of Undulating Swimmers
Nayak, Dev Pradeepkumar
Tarokh, Ali
Khalid, Muhammad Saif Ullah
Fluid Dynamics
Fish display remarkable swimming capabilities through the coordinated interaction of the body and caudal fin, yet the potential role of a passively pitching tail in enhancing hydrodynamic performance remains unresolved. In this work, we evaluate the performance of a carangiform swimmer equipped with either an actively pitching tail or a passively pitching tail. Fluid-structure interactions-based simulations are employed to asses how variations in joint stiffness, damping, and inertia influence thrust generation, power demand, and overall stability at two representative Reynolds numbers of 500 and 5000. The results reveal that actively pitching tails tend to generate greater thrust, while passively pitching tails deliver improved outcomes in terms of the power demand at the lower Reynolds number. Larger pitching amplitudes contribute positively only when associated with higher swimming frequency, when produced by reduced inertia for more flexible joints, they lead to unfavorable effects. At the higher Reynolds number, active tails consistently outperform passive ones, although a small subset of passive cases still achieve favorable performance. Across all cases, a recurring balance emerges, with thrust production and power expenditure varying inversely. These findings clarify the hydrodynamic consequences of passive versus active tail motion and establish design principles for bio-inspired underwater vehicles, where smaller swimmers may benefit from passive tail pitching, while larger swimmers are better served by active control
title Comparative Investigations on Active and Passive Tails of Undulating Swimmers
topic Fluid Dynamics
url https://arxiv.org/abs/2511.03057