Tag: collective dynamics

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Confinement-driven state transition and bistability in schooling fish

B. Lafoux, P. Bernard, B. Thiria, R. Godoy-Diana
Physical Review E, 110(3), 034613 (2024).
doi: 10.1103/PhysRevE.110.034613
arXiv preprint: https://arxiv.org/abs/2401.01850

In this work we have quantified how fish swimming in groups change their behavior based on how crowded they are. We found that fish switch between two main swimming patterns: moving in the same direction or circling like a whirlpool. The amount of space available influences how long the fish stick to each pattern and how often they switch. This research not only helps us understand how fish and other animals behave in groups, but also provides valuable real-world data that can help tuning computer models of group behavior. The findings highlight the importance of considering space limitations when studying how animals move together, which could lead to better understanding of complex group behaviors in nature.

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Far-field hydrodynamic interaction in a group of swimmers

Three-dimensional schools of hydrodynamically axisymmetric swimmers self-propelling at a constant velocity are studied. We introduce a low-order model for the induced velocity based on the far-field approximation. We inquire if, by holding suitable relative positions in the three-dimensional space, the swimmers can reduce the overall energy consumption of the school in comparison with the same number of isolated individuals at the same velocity. We find a considerable (several per cent) energy saving achievable by chain formations. The benefit increases asymptotically with the number of individuals, towards a finite limit that is a function of the minimum allowed spacing between each pair of neighbours.

G. Li, L. Duan, J. Sesterhenn, R. Godoy-Diana, B. Thiria, & D. Kolomenskiy
Journal of Fluid Mechanics, 974, A34 (2023).
doi: 10.1017/jfm.2023.802

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Illuminance-tuned collective motion in fish

B. Lafoux, J. Moscatelli, R. Godoy-Diana & B. Thiria
Communications Biology 6, Article number: 585 (2023)
doi: 10.1038/s42003-023-04861-8

We experimentally investigate the role of illumination on the collective dynamics of a large school (ca. 50 individuals) of Hemigrammus rhodostomus.

Experimental setup: shallow swimming arena with illuminance control and infrared video recording

The structure of the group, defined using two order parameters (milling annd polarization), is quantified while progressively altering the visual range of the fish through controlled cycles of ambient light intensity. We show that, at low light levels, the individuals within the group are unable to form a cohesive group…

while at higher illuminance the degree of alignment of the school correlates with the light intensity. When increasing the illuminance, the school structure is successively characterized by a polarized state…

followed by a highly regular and stable rotational configuration (milling).

Our study shows that vision is necessary to achieve cohesive collective motion for free swimming fish schools, while the short-range lateral line sensing is insufficient in this situation. The present experiment therefore provides new insights into the interaction mechanisms that govern the emergence and intensity of collective motion in biological systems. Watch a full experiment here:

Full paper here:
Lafoux, B., Moscatelli, J., Godoy-Diana, R., Thiria, B. Illuminance-tuned collective motion in fish. Commun Biol 6, 585 (2023).
https://doi.org/10.1038/s42003-023-04861-8

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How lateral-line sensing can enable swimming fish to judge their relative position and kinematic synchronization with a neighbor

Flow field computed around a pair of swimming fish. The pressure and shear-stress signals along the sides of the protagonist fish are monitored while changing the relative position and tail-beat phase lag of the companion fish.

For fish, swimming in group may be favorable to individuals. Several works reported that in a fish school, individuals sense and adjust their relative position to prevent collisions and maintain the group formation. Also, from a hydrodynamic perspective, relative-position and kinematic synchronisation between adjacent fish may considerably influence their swimming performance. Fish may sense the relative-position and tail-beat phase difference with their neighbors using both vision and the lateral-line system, however, when swimming in dark or turbid environments, visual information may become unavailable. To understand how lateral-line sensing can enable fish to judge the relative-position and phase-difference with their neighbors, in this study, based on a verified three-dimensional computational fluid dynamics approach, we simulated two fish swimming adjacently with various configurations. The lateral-line signal was obtained by sampling the surface hydrodynamic stress. The sensed signal was processed by Fast Fourier Transform (FFT), which is robust to turbulence and environmental flow. By examining the lateral-line pressure and shear-stress signals in the frequency domain, various states of the neighboring fish were parametrically identified. Our results reveal that the FFT-processed lateral-line signals in one fish may potentially reflect the relative-position, phase-differences, and the tail-beat frequency of its neighbor. Our results shed light on the fluid dynamical aspects of the lateral-line sensing mechanism used by fish. Furthermore, the presented approach based on FFT is especially suitable for applications in bioinspired swimming robotics. We provide suggestions for the design of artificial systems consisting of multiple stress sensors for robotic fish to improve their performance in collective operation.

Hydrodynamical Fingerprint of a Neighbour in a Fish Lateral Line
G. Li, D. Kolomenskiy, H. Liu, B. Thiria & R. Godoy-Diana Frontiers in Robotics and AI: Bio-Inspired Robotics section 9, 825889 (2022)
doi: 10.3389/frobt.2022.825889

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Synchronized Side-by-Side Swimmers

On the fluid dynamical effects of synchronization in side-by-side swimmers
R. Godoy-Diana, J. Vacher, V. Raspa & B. Thiria
Biomimetics 4(4), 77 (2019)
https://doi.org/10.3390/biomimetics4040077
(in the Special issue “Fluid Dynamic Interactions in Biological and Bioinspired Propulsion”, Editors K. W. Moored and G. V. Lauder)

https://vimeo.com/378101069

We examined experimentally the in-phase and anti-phase synchronized swimming of 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.

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On the energetics and stability of a minimal fish school

On the energetics and stability of a minimal fish school
G. Li, D. Kolomenskiy, H. Liu, B. Thiria & R. Godoy-Diana
PLoS ONE 14(8): e0215265 (2019)
https://doi.org/10.1371/journal.pone.0215265

See also:
On the interference of vorticity and pressure fields of a minimal fish school
G. Li, D. Kolomenskiy, H. Liu, B. Thiria & R. Godoy-Diana
Journal of Aero Aqua Bio-mechanisms 8 (1), 27-33 (2019)
[doi:10.5226/jabmech.8.27]

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.

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PhD defense: Salomé Gutiérrez-Ramos. Acoustic confinement of Escherichia coli: The impact on biofilm formation

PhD defense on October 18th, 2018, 2:30pm, at the PMMH meeting room (Sorbonne Université, Barre Cassan, Bât. A 1er Étage, 7 Quai Saint Bernard, 75005 Paris).

Acoustic confinement of Escherichia coli: The impact on biofilm formation

Brownian or self-propelled particles in aqueous suspensions can be trapped by acoustic fields generated by piezoelectric transducers usually at frequencies in the Megahertz. The obtained confinement allows the study of rich collective behaviours like clustering or spreading dynamics in microgravity-like conditions. The acoustic field induces the levitation of self-propelled particles and provides secondary lateral forces to capture them at nodal planes. Here, we give a step forward in the field Continue reading “PhD defense: Salomé Gutiérrez-Ramos. Acoustic confinement of Escherichia coli: The impact on biofilm formation”

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Intesaaf Ashraf’s PhD defense. Interactions in Collective Fish Swimming

PhD defense on April 4th, 2018, 3pm, at the new PMMH meeting room (Sorbonne Université, Barre Cassan, Bât. A 1er Étage, 7 Quai Saint Bernard, 75005 Paris).

Interactions in Collective Fish Swimming

The question of how individuals in a population organise when living in groups arises for systems as different as a swarm of microorganisms or a flock of seagulls; and the different patterns for moving collectively involve a complex interaction of a wide spectrum of reasons, such as evading predators, optimising food prospection or diminishing energy consumption. The basic ingredient in such problems is the communication mechanism between individuals, that is to say, the way in which two neighbours sense each other, constituting the fabric of social behaviour. In this work we studied the case of fish schooling using a popular aquarium fish, the red nose tetra fish Hemigrammus bleheri. These fish are known to swim in highly cohesive groups and to sense each other both visually and through the lateral line, a system of organs based on the ability of hair cells to detect movement in their environment. In our experiments Continue reading “Intesaaf Ashraf’s PhD defense. Interactions in Collective Fish Swimming”

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Synchronisation and pattern formation in fish swimming

Tetrafish2

Simple phalanx pattern leads to energy saving in cohesive fish schooling
I. Ashraf, H. Bradshaw, T. T. Ha, J. Halloy, R. Godoy-Diana, B. Thiria
PNAS 114 (36) 9599-9604 (2017)
[doi:10.1073/pnas.1706503114]PDF file

Synchronisation and collective swimming patterns in Hemigrammus bleheri
I. Ashraf, R. Godoy-Diana, J. Halloy, B. Collignon, B. Thiria
Journal of the Royal Society Interface 13 20160734 (2016)
[doi:10.1098/rsif.2016.0734] PDF file

The question of how individuals in a population organize when living in groups arises for systems as different as a swarm of microorganisms or a flock of seagulls. The different patterns for moving collectively involve a wide spectrum of reasons, such as evading predators or optimizing food prospection. Also, the schooling pattern has often been associated with an advantage in terms of energy consumption. We use a popular aquarium fish, the red nose tetra fish, Hemigrammus bleheri, which is known to swim in highly cohesive groups, to ana- lyze the schooling dynamics. In our experiments, fish swim in a shallow-water tunnel with controlled velocity, Continue reading “Synchronisation and pattern formation in fish swimming”