School cohesion, speed and efficiency are modulated by the swimmers flapping motion

Heydari, Sina; Kanso, Eva

doi:10.1017/jfm.2021.551

Cited by 15 publications

(24 citation statements)

References 57 publications

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“…This allows them to generate additional thrust and reduce their energy expenditure. Despite visual similarity, the swinging is different from the extensively studied pitching or heaving 30 – 32 in the sense that both lateral and angular positions are achieved by smart orientation of the whole fish with respect to the surrounding flow structures rather than by application of an external force to a propulsive fin. The shape of the fish body in different gaiting phases maximises the propulsive component of force and provides steering to compensate imbalances in the yawing moment.…”

Section: Discussionmentioning

confidence: 93%

An inertial mechanism behind dynamic station holding by fish swinging in a vortex street

Harvey

Muhawenimana

Wilson

et al. 2022

Sci Rep

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Many aquatic and aerial animal species are known to utilise their surrounding flow field and/or the induced flow field of a neighbour to reduce their physical exertion, however, the mechanism by which such benefits are obtained has remained elusive. In this work, we investigate the swimming dynamics of rainbow trout in the wake of a thrust-producing oscillating hydrofoil. Despite the higher flow velocities in the inner region of the vortex street, some fish maintain position in this region, while exhibiting an altered swimming gait. Estimates of energy expenditure indicate a reduction in the propulsive cost when compared to regular swimming. By examining the accelerations of the fish, an explanation of the mechanism by which energy is harvested from the vortices is proposed. Similar to dynamic soaring employed by albatross, the mechanism can be linked to the non-equilibrium hydrodynamic forces produced when fish encounter the cross-flow velocity generated by the vortex street.

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Section: Discussionmentioning

confidence: 93%

An inertial mechanism behind dynamic station holding by fish swinging in a vortex street

Harvey

Muhawenimana

Wilson

et al. 2022

Sci Rep

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“…One important difference is that the fish are composed of a body and fins, with it's caudal fin undergoing a combined heaving and pitching motion. However, recent work has shown that both purely heaving and purely pitching foils experience one-dimensional stability in an in-line arrangement (15), so perhaps the difference in kinematics is not consequential for the existence of stable equilibria. Still, further work should aim to examine the passive stability of truly fish-like swimmers to directly answer this question.…”

Section: Discussionmentioning

confidence: 99%

“…Yet, both the spatial organization (3,8) and temporal synchronization (9)(10)(11) have emerged as major drivers of the hydrodynamic interactions, and, consequently, the energetic cost of locomotion and traveling speed of individuals in a collective. Still, our understanding of the force production and energetics of schooling swimmers is mostly limited to canonical spatial arrangements such as a leader-follower in-line arrangement (12)(13)(14)(15) and a side-by-side arrangement (11,(16)(17)(18), while there are fewer studies of staggered arrangements (19)(20)(21)(22).…”

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confidence: 99%

Two-dimensionally stable self-organization arises in simple schooling swimmers through hydrodynamic interactions

Ormonde¹,

Kurt²,

Mivehchi³

et al. 2021

Preprint

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We present new experiments and free-swimming simulations of a pair of pitching hydrofoils interacting in a simple school. The hydrofoils have an out-of-phase synchronization and their arrangement is varied from in-line to side-by-side arrangements through a series of staggered arrangements representing the two-dimensional interaction plane. It is discovered that there is a two-dimensionally stable equilibrium point for a side-by-side arrangement. In fact, this arrangement is super-stable meaning that hydrodynamic forces will passively maintain this arrangement even under external perturbations and the school as a whole has no net forces acting on, drifting it to one side or the other. Moreover, previously discovered onedimensionally stable equilibria driven by wake vortex interactions are shown to be, in fact, two-dimensionally unstable, at least for an out-of-phase synchronization. Additionally, the stable equilibrium arrangement is verified for freely-swimming foils undergoing dynamic recoil motions. When constrained, the swimmers experience a collective thrust and efficiency increase up to 100% and 40%, respectively, in a side-by-side arrangement. However, in a staggered arrangement where there is direct vortex impingement on a follower, an even higher efficiency improvement of 87% is observed, which is coupled with a 94% increase in the thrust. For freely-swimming foils, the recoil motion attenuates the performance improvements showing a more modest speed and efficiency enhancement of up to 9% and 6%, respectively, when the swimmers are at their stable equilibrium. These newfound schooling performance and stability characteristics suggest that fluid-mediated equilibria may play a role in the control strategies of schooling fish and fish-inspired robots.collective locomotion | hydrodynamic interactions | fish schooling | pattern formation | collective performance M. K. helped design the study, gathered and processed experimental measurements, and drafted the manuscript. A. M. helped design the study, gathered and processed the numerical data, and helped revise the manuscript. K. M. helped design the study, and helped revise the manuscript.

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“…Fish school: The key to understanding fish-schooling behavior lies in making clear the role of fluid medium or flow structures [120][121][122][123]. A single fish can be a good analytical entry point.…”

Section: Intermediate Viewmentioning

confidence: 99%

“…If two fish are arranged in an in-line configuration, the follower can reduce up to 30% energy cost and the leader benefits energetically only for small distances by exploiting independent pitch control of its caudal fin [83,129,130]. Moreover, pitching motions can increase the group efficiency while heaving motions can lead to a slight increase in the swimming speed [122]. In this in-line configuration, Dai discussed the effect of the horizontal spacing and vertical spacing between two fish [131]; Verma improved coordinated patterns through deep reinforcement learning [132]; Li found that the follower can exhibit 'vortex phase matching' strategy [133].…”

Section: Intermediate Viewmentioning

confidence: 99%

Research Development on Fish Swimming

Jiang

2022

Chin. J. Mech. Eng.

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Fishes have learned how to achieve outstanding swimming performance through the evolution of hundreds of millions of years, which can provide bio-inspiration for robotic fish design. The premise of designing an excellent robotic fish include fully understanding of fish locomotion mechanism and grasp of the advanced control strategy in robot domain. In this paper, the research development on fish swimming is presented, aiming to offer a reference for the later research. First, the research methods including experimental methods and simulation methods are detailed. Then the current research directions including fish locomotion mechanism, structure and function research and bionic robotic fish are outlined. Fish locomotion mechanism is discussed from three views: macroscopic view to find a unified principle, microscopic view to include muscle activity and intermediate view to study the behaviors of single fish and fish school. Structure and function research is mainly concentrated from three aspects: fin research, lateral line system and body stiffness. Bionic robotic fish research focuses on actuation, materials and motion control. The paper concludes with the future trend that curvature control, machine learning and multiple robotic fish system will play a more important role in this field. Overall, the intensive and comprehensive research on fish swimming will decrease the gap between robotic fish and real fish and contribute to the broad application prospect of robotic fish.

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School cohesion, speed and efficiency are modulated by the swimmers flapping motion

Abstract: Abstract

Cited by 15 publications

References 57 publications

An inertial mechanism behind dynamic station holding by fish swinging in a vortex street

An inertial mechanism behind dynamic station holding by fish swinging in a vortex street

Two-dimensionally stable self-organization arises in simple schooling swimmers through hydrodynamic interactions

Research Development on Fish Swimming

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