Tag: swimming

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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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Form and function of anguilliform swimming: a review

V. Stin, R. Godoy-Diana, X. Bonnet, & A. Herrel
Biological Reviews (2024)
doi: 10.1111/brv.13116

Anguilliform swimmers are long and narrow animals that propel themselves by undulating their bodies. Observations in nature and recent investigations suggest that anguilliform swimming is highly efficient. However, understanding the underlying reasons for the efficiency of this type of locomotion requires interdisciplinary studies spanning from biology to hydrodynamics. Regrettably, these different fields are rarely discussed together, which hinders our ability to understand the repeated evolution of this swimming mode in vertebrates. This review compiles the current knowledge of the anatomical features that drive anguilliform swimming, compares the resulting kinematics across a wide range of anguilliform swimmers, and describes the resulting hydrodynamic interactions using data from both in vivo experiments and computational studies.

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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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Volumetric velocimetry of the wake of a swimming snake

We describe a method for measuring the 3D vortical structures produced by an anguilliform swimmer using volumetric velocimetry. The wake of freely swimming dice snakes (Natrix tessellata) was quantified, revealing the creation of multiple vortices along the body of the snake due to its undulation. The 3D structure of the vortices generally consisted of paired vortex tubes, some of which were linked together to form a hairpin structure. The observations match predictions from computational fluid dynamic studies of other anguilliform swimmers. Quantitative measurements allowed us to study vortex circulation and size, and global kinetic energy of the flow, which varied with swimming speed, vortex topology and individual characteristics. Our findings provide a baseline for comparing wake structures of snakes with different morphologies and ecologies and investigating the energetic efficiency of anguilliform swimming.


V. Stin, R. Godoy-Diana, X. Bonnet, & A. Herrel. Measuring the 3D wake of swimming snakes (Natrix tessellata) using volumetric velocimetry.
Journal of Experimental Biology, 226, jeb245929 (2023)
doi: 10.1242/jeb.245929

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Special issue: Bioinspired fluid-structure interaction

https://iopscience.iop.org/journal/1748-3190/page/Bioinspired-Fluid-Structure-Interaction

Fluid-structure interaction (FSI) studies the interaction between fluid and solid objects. It helps understand how fluid motion affects solid objects and vice versa. FSI research is important in engineering applications such as aerodynamics, hydrodynamics, and structural analysis. It has been used to design efficient systems such as ships, aircraft, and buildings. FSI in biological systems has gained interest in recent years for understanding how organisms interact with their fluidic environment. Our special issue features papers on various biological and bio-inspired FSI problems.

S. Jung & R. Godoy-Diana
Bioinspiration & biomimetics 18, 030401 (2023)
Editorial article: 10.1088/1748-3190/acc778

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Intermittent vs. continuous swimming: An optimization tale

G. Li, D. Kolomenskiy, H. Liu, R. Godoy-Diana & B. Thiria
Physical Review Fluids 8, 013101 (2023)
doi: 10.1103/PhysRevFluids.8.013101
see also in Physics Magazine: Why Fish Swim Intermittently

Intermittent swimming, also termed “burst-and-coast swimming,” has been reported as a strategy for fish to enhance their energetical efficiency. Intermittent swimming involves additional control parameters, which complexifies its understanding by means of quantitative and parametrical analysis, in comparison with continuous swimming. In this study, we used a hybrid computational fluid dynamic (CFD) model to assess the swimming performance in intermittent swimming parametrically and quantitatively. A Navier-Stokes solver is applied to construct a database in the multidimensional space of the control parameters to connect the undulation kinematics to swimming performance. Based on the database, an indirect numerical approach named “gait assembly” is used to generate arbitrary burst-and-coast gaits to explore the parameter space. Our simulations directly measured the hydrodynamics and energetics under the unsteady added-mass effect during burst-and-coast swimming. The results suggest that the instantaneous power of burst is basically determined by undulatory kinematics. The results show that the energetical performance of burst-and-coast swimming can be better than that of continuous swimming, but also that an unoptimized burst-and-coast gait may become very energetically expensive. These results shed light on the mechanisms at play in intermittent swimming, enabling us to better understand fish behavior and to propose design guidelines for fishlike robots.

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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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Hydrodynamics of the frontal strike in aquatic snakes

Hydrodynamics of the frontal strike in aquatic snakes: drag, added mass and the consequences for prey capture success

 

M. Segall, A. Herrel & R. Godoy-Diana
Bioinspiration & Biomimetics 14, 036005 (2019)
[doi:10.1088/1748-3190/ab0316]
bioRxiv preprint: https://doi.org/10.1101/411850

Transient locomotion under water is highly constrained by drag and added mass, yet some aquatic snakes catch their prey using a fast forward acceleration, with the mouth opened. These aquatic snakes show a convergence of their head shape in comparison with closely related species that do not forage under water. As both drag and added mass are related to some extent to the shape of the moving object, we explored how shape impacts the hydrodynamic forces applied to the head of a snake during a prey capture event. We compared two 3D- Continue reading “Hydrodynamics of the frontal strike in aquatic snakes”

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Review paper: Fluid dynamic drag in animal swimming and flying

On the diverse roles of fluid dynamic drag in animal swimming and flying
R. Godoy-Diana & B. Thiria
Journal of the Royal Society Interface 15 20170715 (2018)
[doi:10.1098/rsif.2017.0715]

Questions of energy dissipation or friction appear immediately when addressing the problem of a body moving in a fluid. For the most simple problems, involving a constant steady propulsive force on the body, a straightforward relation can be established balancing this driving force with a skin friction or form drag, depending on the Reynolds number and body geometry. This elementary relation closes the full dynamical problem and sets, for instance, average cruising velocity or energy cost. Continue reading “Review paper: Fluid dynamic drag in animal swimming and flying”

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Flapping elastic plates as a model of fish-like swimmers

Modelling of an actuated elastic swimmer
M. Piñeirua, B. Thiria & R. Godoy-Diana
Journal of Fluid Mechanics 829 731-750 (2017)
[doi:10.1017/jfm.2017.570]PDF file

We studied the force production dynamics of undulating elastic plates as a model for fish-like inertial swimmers. Using a beam model coupled with Lighthill’s large-amplitude elongated-body theory, we explore different localised actuations at one extremity of the plate (heaving, pitching and a combination of both) in order to quantify the reactive and resistive contributions to the thrust. The latter has the Continue reading “Flapping elastic plates as a model of fish-like swimmers”

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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”

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Resistive thrust production can be as crucial as added mass mechanisms for inertial undulatory swimmers

resistive_vs_reactiveResistive thrust production can be as crucial as added mass mechanisms for inertial undulatory swimmers
M. Piñeirua, R. Godoy-Diana & B. Thiria
Physical Review E 92 021001(R) (2015).
[doi:10.1103/PhysRevE.92.021001] arXiv

We address here a crucial point regarding the description of moderate to high Reynolds numbers aquatic swimmers. For decades, swimming animals have been classified in two different families of propulsive mechanisms based on the Reynolds number: the resistive swimmers, using local friction to produce the necessary thrust force for locomotion at low Reynolds number, and the reactive swimmers, lying in the high Reynolds range, and using added mass acceleration (described by perfect fluid theory). Continue reading “Resistive thrust production can be as crucial as added mass mechanisms for inertial undulatory swimmers”

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Undulatory swimming near a wall

wall_effect_visuLarge-amplitude undulatory swimming near a wall
R. Fernández-Prast, V. Raspa, B. Thiria, F. Huera-Huarte & R. Godoy-Diana. Bioinspiration and Biomimetics 10 016003 (2015).

doi:10.1088/1748-3190/10/1/016003

[PDF file]

We study experimentally the propulsive dynamics of flexible undulating foils in a self-propelled swimming configuration near a wall. Measurements of swimming speed and propulsive force are performed, together with full recordings of the elastic wave kinematics and particle image velocimetry. Continue reading “Undulatory swimming near a wall”

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Habilitation à diriger des recherches (HDR)

Bio-inspired swimming and flying – Vortex dynamics and fluid/structure interaction

Ramiro Godoy-Diana
Habilitation à diriger des recherches, Université Pierre et Marie Curie, 2014.
[hal.archives-ouvertes.fr]

PDF file here (19.4 MB)

The present document, prepared in view of obtaining the Habilitation à diriger des recherches, reviews my main research subject at PMMH since 2006, which concerns the study of swimming and flying inspired by nature. Canonical examples of flapping flight and undulatory swimming are explored using simplified experimental models as a starting point. This allows for the discussion of some fundamental questions related to the physics of bio-inspired locomotion at “intermediate” Reynolds numbers. In particular, we address the strong fluid-structure interactions that arise in these problems, where we have focused on: simplified models of flapping foils in hydrodynamic tunnel experiments, especially in the dynamics of vorticity in the wake of an oscillating foil ; mechanical models of flapping flyers with flexible wings in a self-propelled configuration (in the spirit of the pioneer experiments of Etienne-Jules Marey), as well as novel experimental models of undulatory swimming.
Continue reading “Habilitation à diriger des recherches (HDR)”

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Drag in undulatory swimmers

vortices_foilsVortex-induced drag and the role of aspect ratio in undulatory swimmers
V. Raspa, S. Ramananarivo, B. Thiria & R. Godoy-Diana. Physics of Fluids, 26 : 041701 (2014).

During cruising, the thrust produced by a self-propelled swimmer is balanced by a global drag force. For a given object shape, this drag can involve skin friction or form drag, both being well-documented mechanisms. However, for swimmers whose shape is changing in time, the question of drag is not yet clearly established. Continue reading “Drag in undulatory swimmers”

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Propagating waves in bounded elastic media

fig_beamsPropagating waves in bounded elastic media: an application to the efficiency of bio-inspired swimmers
S. Ramananarivo, R. Godoy-Diana & B. Thiria.
EPL, 105 : 54003 (2014).

Confined geometries usually involve reflected waves interacting together to form a spatially stationary pattern. Our recent study on the locomotion of a self-propelled elastic swimmer on a free surface [Ramananarivo et al. 2013], however, has shown that propagating wave kinematics can naturally emerge in a forced elastic rod, even with boundary conditions involving significant reflections. This particular behavior is observed only in the presence of strong damping. Continue reading “Propagating waves in bounded elastic media”

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Passive elastic mechanism to mimic fish-muscles action in anguilliform swimming

nageur_Ramananarivo_etalPassive elastic mechanism to mimic fish-muscles action in anguilliform swimming
S. Ramananarivo; R. Godoy-Diana & B. Thiria.
Journal of the Royal Society Interface 10 : 20130667 (2013).

Abstract: Swimmers in nature use body undulations to generate propulsive and maneuvering forces. The an- guilliform kinematics is driven by muscular actions all along the body, involving a complex temporal and spatial coordination of all the local actuations. Such swimming kinematics can be reproduced artificially, in a simpler way, by using passively the elasticity of the body. Here we present experiments on self-propelled elastic swimmers at a free surface in the inertial regime. Continue reading “Passive elastic mechanism to mimic fish-muscles action in anguilliform swimming”

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Topology-induced effect in biomimetic propulsive wakes

two_flapsTopology-induced effect in biomimetic propulsive wakes
V. Raspa; R. Godoy-Diana & B. Thiria.
Journal of Fluid Mechanics, 729: 377-387 (2013).

Abstract: It is known that the wake pattern observed in a cross-section behind swimming or flying animals is typically characterized by the presence of periodical vortex shedding. However, depending on species, propulsive wakes can differ according to the spatial ordering of the main vortex structures. We conducted a very precise experiment to analyse the role of the topology of the wake in the generation of propulsion by comparing two prototypical cases in a quasi-two-dimensional view. Continue reading “Topology-induced effect in biomimetic propulsive wakes”

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Stabilizing effect of flexibility in the wake of a flapping foil

flex_vs_rig_jetStabilizing effect of flexibility in the wake of a flapping foil
C. Marais; B Thiria; Wesfreid, J. E. & R. Godoy-Diana.
Journal of Fluid Mechanics, 710 : 659-669 (2012).

Abstract: The wake of a flexible foil undergoing pitching oscillations in a low-speed hydrodynamic tunnel is used to examine the effect of chordwise foil flexibility in the dynamical features of flapping-based propulsion. Continue reading “Stabilizing effect of flexibility in the wake of a flapping foil”