On the interference of vorticity and pressure fields of a minimal fish school

Li, Gen; Kolomenskiy, Dmitry; Líu, Hao; Thiria, Benjamin; Godoy-Diana, Ramiro

doi:10.5226/jabmech.8.27

“…(d) Multi-blocked computational grid system consists of local fine-scale body-fitted grids (dimension: 121 × 97 × 20) plus a large stationary global grid (dimension: variant). Reprinted from [35] under a CC BY license, with permission from the Society of Aero Aqua Bio-mechanisms, original copyright 2019.…”

Section: Methodsmentioning

confidence: 99%

“…(a) δx = 0.2 L , δy = 1.25 L , δϕ = 0; (b) δx = 0.5 L , δy = 0, δϕ = T /2. For more examples of the wake topology, see [35]. …”

Section: Introductionmentioning

confidence: 99%

On the energetics and stability of a minimal fish school

Li

¹

,

Kolomenskiy

²

,

H

³

et al. 2019

Self Cite

View full text Add to dashboard Cite

The physical basis for fish schooling is examined using three-dimensional numerical simulations of a pair of swimming fish, with kinematics and geometry obtained from experimental data. Energy expenditure and efficiency are evaluated using a cost of transport function, while the effect of schooling on the stability of each swimmer is examined by probing the lateral force and the lateral and longitudinal force fluctuations. We construct full maps of the aforementioned quantities as functions of the spatial pattern of the swimming fish pair and show that both energy expenditure and stability can be invoked as possible reasons for the swimming patterns and tail-beat synchronization observed in real fish. Our results suggest that high cost of transport zones should be avoided by the fish. Wake capture may be energetically unfavorable in the absence of kinematic adjustment. We hereby hypothesize that fish may restrain from wake capturing and, instead, adopt side-to-side configuration as a conservative strategy, when the conditions of wake energy harvesting are not satisfied. To maintain a stable school configuration, compromise between propulsive efficiency and stability, as well as between school members, ought to be considered.

show abstract

“…Conceptually, the setup with two swimmers that we study in the present paper is one of the simplest model realizations of the minimal school [24,25] and has been designed to examine the complex flow dynamics that arises due to the undulation kinematics of the two swimmers. Recent experiments on real fish in a swimming channel with imposed velocity have shown that fish favor a synchronized kinematics with their nearest neighbors as the swimming speed of the school increases [17,18].…”

Section: Introductionmentioning

confidence: 99%

On the Fluid Dynamical Effects of Synchronization in Side-by-Side Swimmers

Godoy-Diana

¹

,

Vacher

²

,

Raspa

³

et al. 2019

Self Cite

View full text Add to dashboard Cite

In-phase and anti-phase synchronization of neighboring swimmers is examined experimentally using two self-propelled independent flexible foils swimming side-by-side in a water tank. The foils are actuated by pitching oscillations at one extremity—the head of the swimmers—and the flow engendered by their undulations is analyzed using two-dimensional particle image velocimetry in their frontal symmetry plane. Following recent observations on the behavior of real fish, we focus on the comparison between in-phase and anti-phase actuation by fixing all other geometric and kinematic parameters. We show that swimming with a neighbor is beneficial for both synchronizations tested, as compared to swimming alone, with an advantage for the anti-phase synchronization. We show that the advantage of anti-phase synchronization in terms of swimming performance for the two-foil “school” results from the emergence of a periodic coherent jet between the two swimmers.

show abstract

“…Halsey et al [14] examined how water turbulence affected the tail beat 34 frequency of sea bass Dicentrarchus labrax swimming in schools of different size. They 35 reported a trend for attenuation of energy advantages which they explained by frequent 36 short-term changes in fish position mediated by the turbulence. At the same time, they 37 recognized that turbulence could modify the relationship between tail beat frequency 38 and rate of oxygen consumption.…”

mentioning

confidence: 99%

“…(a) δx = 0.2L, δy = 1.25L, δφ = 0; (b) δx = 0.5L, δy = 0, δφ = T /2. For more examples of the wake topology, see [35].…”

mentioning

confidence: 99%

On the energetics and stability of a minimal fish school

Li

¹

,

Kolomenskiy

²

,

Líu

³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

The physical basis for fish schooling is examined using three-dimensional numerical simulations of a pair of swimming fish, with kinematics and geometry obtained from experimental data. Energy expenditure and efficiency are evaluated using a cost of transport function, while the effect of schooling on the stability of each swimmer is examined by probing the lateral force and the lateral and longitudinal force fluctuations. We construct full maps of the aforementioned quantities as functions of the spatial pattern of the swimming fish pair and show that both energy expenditure and stability can be invoked as possible reasons for the swimming patterns and tail-beat synchronization observed in real fish. Our results suggest that high cost of transport zones should be avoided by the fish. Wake capture may be energetically unfavorable in the absence of kinematic adjustment. We hereby hypothesize that fish may restrain from wake capturing and, instead, adopt side-to-side configuration as a conservative strategy, when the conditions of wake energy harvesting are not satisfied. To maintain a stable school configuration, compromise between propulsive efficiency and stability, as well as between school members, ought to be considered. 2 result from complex social reasons [1-4]. Depending on the species, animals aggregate 3 and modulate group cohesion to improve foraging and reproductive success, avoid 4 predators or facilitate predation. Global cohesive decision and action for the whole 5 group result from different types of interaction at the local scale. Fish schools, for 6 instance, are an archetypal example of how local interactions lead to complex global 7 decisions and motions [5]. Fish interact through vision but also by sensing the 8 surrounding flow using their lateral line system [6]. From the fluid dynamics perspective, 9 hydrodynamic interactions between neighbors have often been associated with swimming 10 efficiency strategies, considering how each individual in the school is affected by the 11 vortical flows produced by its neighbors. Breder [7] already recognized the importance 12 of this issue, and more recent works have described how fish make use of vortices when 13 swimming through an unsteady flow, whether produced by neighboring fish or by other 14 March 27, 2019 1/14 features in the environment (see e.g. the review by Liao [8]). Concerning collaborative 15interactions between swimming fish, the first clear picture was proposed in the early 16 70's by Weihs' pioneering work [9]. He focused on interactions within a two-dimensional 17 layer of a three-dimensional school, and proposed an idealized two-dimensional model in 18 which each individual in the fish school places itself to benefit from the wakes generated 19 by its two nearest neighbors, giving rise to a precise diamond-like pattern. 20Weihs' theory has been followed by extensive experimental verification generally 21 comforting the idea of decreased energetic cost of locomotion in fish schools. Thus, 50We are only aware of two previous three-di...

show abstract

On the interference of vorticity and pressure fields of a minimal fish school

Cited by 8 publications

References 16 publications

On the energetics and stability of a minimal fish school

On the energetics and stability of a minimal fish school

On the Fluid Dynamical Effects of Synchronization in Side-by-Side Swimmers

On the energetics and stability of a minimal fish school

Contact Info

Product

Resources

About