Role of body stiffness in undulatory swimming: Insights from robotic and computational models

Tytell, Eric D.; Leftwich, Megan C.; Hsu, Chia Yu; Griffith, Boyce E.; Cohen, Avis H.; Smits, Alexander J.; Hamlet, Christina; Fauci, Lisa

doi:10.1103/physrevfluids.1.073202

Cited by 66 publications

(59 citation statements)

References 44 publications

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“…The impact of flexibility on propulsion has been the focus of research in many different biological systems, such as swimming jellyfish (Demont & Gosline 1988;Megill, Gosline & Blake 2005;Colin et al 2012;Hoover & Miller 2015;Hoover, Griffith & Miller 2017), swimming lamprey (Tytell et al 2010;Tytell, Hsu & Fauci 2014;Hamlet, Fauci & Tytell 2015;Tytell et al 2016) and flying insects (Miller & Peskin 2009). In addition, Leftwich et al (2012) examined the effect of a flexible tail on the swimming performance of a robotic lamprey.…”

Section: Introductionmentioning

confidence: 99%

“…A model of lamprey locomotion that does capture the full elastohydrodynamic coupling in a Navier-Stokes fluid (Tytell et al 2010) actuated by detailed muscle mechanics (Hamlet et al 2015) has been used to explore the role of flexibility in swimming performance, but only in a two-dimensional domain. While two-dimensional models do capture many features of the three-dimensional system (de Sousa & Allen 2011; Shoele & Zhu 2012;Zhu, He & Zhang 2014;Tytell et al 2016;Andersen et al 2017), the spatio-temporal evolution of the vortex structures in the wake of a swimmer or a flapping panel are affected by the spanwise geometry of the panel (Buchholz & Smits 2006, 2008Green & Smits 2008;Green et al 2011;Van Buren et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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Swimming performance, resonance and shape evolution in heaving flexible panels

et al. 2018

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Many animals that swim or fly use their body to accelerate the fluid around them, transferring momentum from their flexible bodies and appendages to the surrounding fluid. The kinematics that emerge from this transfer result from the coupling between the fluid and the active and passive material properties of the flexible body or appendages. To elucidate the fundamental features of the elastohydrodynamics of flexible appendages, recent physical experiments have quantified the propulsive performance of flexible panels that are actuated on their leading edge. Here we present a complementary computational study of a three-dimensional flexible panel that is heaved sinusoidally at its leading edge in an incompressible, viscous fluid. These high-fidelity numerical simulations enable us to examine how propulsive performance depends on mechanical resonance, fluid forces, and the emergent panel deformations. Moreover, the computational model does not require the tethering of the panel. We therefore compare the thrust production of tethered panels to the forward swimming speed of the same panels that can move forward freely. Varying both the passive material properties and the heaving frequency of the panel, we find that local peaks in trailing edge amplitude and forward swimming speed coincide and that they are determined by a non-dimensional quantity, the effective flexibility, that arises naturally in the Euler–Bernoulli beam equation. Modal decompositions of panel deflections reveal that the amplitude of each mode is related to the effective flexibility. Panels of different material properties that are actuated so that their effective flexibilities are closely matched have modal contributions that evolve similarly over the phase of the heaving cycle, leading to similar vortex structures in their wakes and comparable thrust forces and swimming speeds. Moreover, local peaks in the swimming speed and trailing edge amplitude correspond to peaks in the contributions of the different modes. This computational study of freely swimming flexible panels gives further insight into the role of resonance in swimming performance that is important in the engineering and design of robotic propulsors. Moreover, we view this reduced model and its comparison to laboratory experiments as a building block and validation for a more comprehensive three-dimensional computational model of an undulatory swimmer that will couple neural activation, muscle mechanics and body elasticity with the surrounding viscous, incompressible fluid.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Swimming performance, resonance and shape evolution in heaving flexible panels

et al. 2018

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“…Zhang, Yu & Tong (2014) provided a prediction of fish body's visco-elastic properties and related muscle mechanical behaviour in vivo based on a continuous beam model (Zhang, Yu & Tong, 2014). Real fish are able to adjust their body stiffness at specific positions in order to optimise their swimming performance such as the maximum forward speed and minimum energy cost (Tytell et al, 2016). However, the distribution of visco-elastic properties, that is stiffness and damping coefficients along the fish body, are difficult to measure precisely, thus the mutual contributions from visco-elastic properties to the optimised swimming performance cannot be determined individually.…”

Section: Discussionmentioning

confidence: 99%

Quantification of the influence of drugs on zebrafish larvae swimming kinematics and energetics

Zhao

Xiao

et al. 2020

PeerJ

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The use of zebrafish larvae has aroused wide interest in the medical field for its potential role in the development of new therapies. The larvae grow extremely quickly and the embryos are nearly transparent which allows easy examination of its internal structures using fluorescent imaging techniques. Medical treatment of zebrafish larvae can directly influence its swimming behaviours. These behaviour changes are related to functional changes of central nervous system and transformations of the zebrafish body such as muscle mechanical power and force variation, which cannot be measured directly by pure experiment observation. To quantify the influence of drugs on zebrafish larvae swimming behaviours and energetics, we have developed a novel methodology to exploit intravital changes based on observed zebrafish locomotion. Specifically, by using an in-house MATLAB code to process the recorded live zebrafish swimming video, the kinematic locomotion equation of a 3D zebrafish larvae was obtained, and a customised Computational Fluid Dynamics tool was used to solve the fluid flow around the fish model which was geometrically the same as experimentally tested zebrafish. The developed methodology was firstly verified against experiment, and further applied to quantify the fish internal body force, torque and power consumption associated with a group of normal zebrafish larvae vs. those immersed in acetic acid and two neuroactive drugs. As indicated by our results, zebrafish larvae immersed in 0.01% acetic acid display approximately 30% higher hydrodynamic power and 10% higher cost of transport than control group. In addition, 500 μM diphenylhydantoin significantly decreases the locomotion activity for approximately 50% lower hydrodynamic power, whereas 100 mg/L yohimbine has not caused any significant influences on 5 dpf zebrafish larvae locomotion. The approach has potential to evaluate the influence of drugs on the aquatic animal’s behaviour changes and thus support the development of new analgesic and neuroactive drugs.

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“…Mean fiber angle in the posterior of the trunk ("posterior") was significantly lower than anterior ("anterior") and midlateral ("midlateral") fiber angles more elongate species with shorter propulsive wavelengths, while higher skin stiffness is associated with species that produce longer propulsive wavelengths and more thrust at the caudal fin. Anguilliform swimmers, including anguillid eels and the penpoint gunnel, engage in relatively slow locomotor speeds and whole-body undulations that consist of more than one waveform (Donatelli, Summers, & Tytell, 2017;van Ginneken et al, 2005). Their skin stiffness is reduced compared to snapper and coho salmon, both subcarangiform swimmers, and pompano, a carangiform swimmer.…”

Section: Materials Properties and Swimming Mechanicsmentioning

confidence: 99%

“…Thus, if the skin contributes to a hydrostat system, we would expect stiffness to vary across taxa according to swimming speed and kinematic pattern, just as our preliminary results suggest. Furthermore, body stiffness is a property that has different optima for high accelerations or low cost of transport, with stiffer bodies capable of faster accelerations at higher energetic demands, while less stiff bodies are capable of more modest accelerations that incur lower energetic costs (Tytell et al, 2016;Tytell, Hsu, Williams, Cohen, & Fauci, 2010).…”

Section: Materials Properties and Swimming Mechanicsmentioning

confidence: 99%

Skin stiffness in ray‐finned fishes: Contrasting material properties between species and body regions

Kenaley

Sanin

Ackerman

et al. 2018

Journal of Morphology

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The skin of aquatic vertebrates surrounds all the mechanical lineages of the body and must, therefore, play an important role in locomotion. A cross-woven collagenous dermal design has converged across several clades of vertebrates. Despite this intriguing pattern, the biomechanical role of skin in swimming fishes remains largely unknown. A direct force transmission role for fish skin has been proposed, a hypothesis that is supported by the arrangement of the connective tissues linking the skin to the axial musculature. To evaluate this direct force-transmission hypothesis, we undertook hundreds of uniaxial tensile tests on skin samples from coho salmon (Oncorhynchus kisutch), Florida pompano (Trachinotus carolinus), and red snapper (Lutjanus campechanus). To do this, we developed highly precise, low-cost, custom-built material testing units. To augment our data, we also assembled a data set of skin stiffness of four additional species of actinopterygians fishes from previously published studies. We found that stiffness varies significantly between species and that the skin of our study species was increasingly stiff along a rostrocaudal gradient. Placing our results in the context of the limited body of previous work, we found that species with lower skin stiffness exhibit shorter propulsive wavelengths and low thrust production at the caudal fin and species with higher skin stiffness possess longer propulsive wavelengths and high thrust production at the caudal fin. In addition, we found that mean collagen fiber angle was close to 50° and that fiber angle was lower in posterior samples than in anterior and midlateral samples. Taken as a whole, our mechanical and morphological results support the hypothesis that the skin functions as an important direct force-transmission device in actinopterygians whereby muscular force generated in anterior myotomes is transmitted to the posterior of the body through the increasingly stiff skin.

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Role of body stiffness in undulatory swimming: Insights from robotic and computational models

Cited by 66 publications

References 44 publications

Swimming performance, resonance and shape evolution in heaving flexible panels

Swimming performance, resonance and shape evolution in heaving flexible panels

Quantification of the influence of drugs on zebrafish larvae swimming kinematics and energetics

Skin stiffness in ray‐finned fishes: Contrasting material properties between species and body regions

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