Hydrodynamic performance of slender swimmer: effect of travelling wavelength

Chao, Li-Ming; Alam, Md. Mahbub; Cheng, Liang

doi:10.1017/jfm.2022.624

Cited by 23 publications

(5 citation statements)

References 74 publications

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“…Fish also adjust their wavelength when encountering a von-Karman vortex street 23 . Numerical simulations of waving foils suggest that an increase in wavelength increases the mean thrust produced, and a decrease in the wavelength leads to smaller fluctuations in the thrust 24 – 26 . An optimum wavelength-to-tail amplitude ratio results in maximum thrust production in a robotic platform and numerical simulations 27 , 28 , and most undulatory natural swimmers swim near this optimum ratio 29 .…”

Section: Introductionmentioning

confidence: 99%

Identification of the trade-off between speed and efficiency in undulatory swimming using a bio-inspired robot

Anastasiadis,

Paez,

Melo

et al. 2023

Sci Rep

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Anguilliform swimmers, like eels or lampreys, are highly efficient swimmers. Key to understanding their performances is the relationship between the body’s kinematics and resulting swimming speed and efficiency. But, we cannot prescribe kinematics to living fish, and it is challenging to measure their power consumption. Here, we characterise the swimming speed and cost of transport of a free-swimming undulatory bio-inspired robot as we vary its kinematic parameters, including joint amplitude, body wavelength, and frequency. We identify a trade-off between speed and efficiency. Speed, in terms of stride length, increases for increasing maximum tail angle, described by the newly proposed specific tail amplitude and reaches a maximum value around the specific tail amplitude of unity. Efficiency, in terms of the cost of transport, is affected by the whole-body motion. Cost of transport decreases for increasing travelling wave-like kinematics, and lower specific tail amplitudes. Our results suggest that live eels tend to choose efficiency over speed and provide insights into the key characteristics affecting undulatory swimming performance.

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Section: Introductionmentioning

confidence: 99%

Identification of the trade-off between speed and efficiency in undulatory swimming using a bio-inspired robot

Anastasiadis,

Paez,

Melo

et al. 2023

Sci Rep

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show abstract

“…The effects of , and on are shown in figure 5, where decreases with increasing and/or , but it increases with increasing . As discussed in Chao, Alam & Cheng (2022), an increase in tailbeat amplitude requires more input power. A larger value of also hinders the flow passing around the foil.…”

Section: Resultsmentioning

confidence: 89%

Hydrodynamics and scaling laws for intermittent S-start swimming

Yang,

Wu,

Khedkar

et al. 2024

J. Fluid Mech.

Self Cite

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The hydrodynamics of a self-propelling swimmer undergoing intermittent S-start swimming are investigated extensively with varying duty cycle $DC$ , swimming period $T$ , and tailbeat amplitude $A$ . We find that the steady time-averaged swimming speed $\bar {U}_x$ increases directly with $A$ , but varies inversely with $DC$ and $T$ , where there is a maximal improvement of $541.29\,\%$ over continuous cruising swimming. Our results reveal two scaling laws, in the form of input versus output relations, that relate the swimmer's kinematics to its hydrodynamic performance: swimming speed and efficiency. A smaller $DC$ causes increased fluctuations in the swimmer's velocity generation. A larger $A$ , on the other hand, allows the swimmer to reach steady swimming more quickly. Although we set out to determine scaling laws for intermittent S-start swimming, these scaling laws extend naturally to burst-and-coast and continuous modes of swimming. Additionally, we have identified, categorized and linked the wake structures produced by intermittent S-start swimmers with their velocity generation.

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“…Numerical simulations of waving foils suggest that an increase in wavelength increases the mean thrust produced, and a decrease in the wavelength leads to smaller fluctuations in the thrust [34][35][36] . An optimum wavelength-to-tail amplitude ratio results in maximum thrust production in a robotic platform and numerical simulations 37,38 , and most undulatory natural swimmers swim near this optimum ratio 39 .…”

Section: Introductionmentioning

confidence: 99%

Identification of the trade-off between speed and efficiency in undulatory swimming using a bio-inspired robot

Anastasiadis

Paez

Melo³

et al. 2023

Preprint

View full text Add to dashboard Cite

Anguilliform swimmers, like eels or lampreys, are highly efficient swimmers. Key to understanding their performances is the relationship between the body's kinematics and resulting swimming speed and efficiency. But, we cannot prescribe kinematics to living fish, and it is challenging to measure their power consumption. Here, we characterise the swimming speed and cost of transport of a free-swimming undulatory bio-inspired robot as we vary its kinematic parameters, including joint amplitude, body wavelength, and frequency. We identify a trade-off between speed and efficiency. Speed, in terms of stride length, scales with the maximum tail angle, described by the newly proposed specific tail amplitude and reaches a maximum value around the specific tail amplitude of unity. Efficiency needs a whole-body motion, travelling wave-like kinematics, and lower specific tail amplitudes. Our results suggest that live eels choose efficiency over speed and provide insights into the key characteristics affecting undulatory swimming performance.

show abstract

Hydrodynamic performance of slender swimmer: effect of travelling wavelength

Cited by 23 publications

References 74 publications

Identification of the trade-off between speed and efficiency in undulatory swimming using a bio-inspired robot

Identification of the trade-off between speed and efficiency in undulatory swimming using a bio-inspired robot

Hydrodynamics and scaling laws for intermittent S-start swimming

Identification of the trade-off between speed and efficiency in undulatory swimming using a bio-inspired robot

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