On the motive mechanism of snakes and fish

Kuznetsov, V. M.; Lugovtsov, B. A.; Sher, Yuh‐Pyng

doi:10.1007/bf00291937

Cited by 20 publications

(19 citation statements)

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“…This report will focus on lateral undulation, whose utility to locomotion by snakes has been previously described on the basis of push points: Snakes slither by driving their flanks laterally against neighboring rocks and branches found along the ground (6)(7)(8)(9)(10)(11). This key assumption has informed numerous theoretical analyses (12)(13)(14)(15)(16)(17) and facilitated the design of snake robots for search-and-rescue operations. Previous investigators (7,9,18,19) have suggested that the frictional anisotropy of the snake's belly scales might play a role in locomotion over flat surfaces.…”

mentioning

confidence: 99%

The mechanics of slithering locomotion

Nirody

Scott

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

347

421

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In this experimental and theoretical study, we investigate the slithering of snakes on flat surfaces. Previous studies of slithering have rested on the assumption that snakes slither by pushing laterally against rocks and branches. In this study, we develop a theoretical model for slithering locomotion by observing snake motion kinematics and experimentally measuring the friction coefficients of snakeskin. Our predictions of body speed show good agreement with observations, demonstrating that snake propulsion on flat ground, and possibly in general, relies critically on the frictional anisotropy of their scales. We have also highlighted the importance of weight distribution in lateral undulation, previously difficult to visualize and hence assumed uniform. The ability to redistribute weight, clearly of importance when appendages are airborne in limbed locomotion, has a much broader generality, as shown by its role in improving limbless locomotion.friction ͉ locomotion ͉ snake L imbless creatures are slender and flexible, enabling them to use methods of locomotion that are fundamentally different from the more commonly studied flying, swimming, walking, and running used by similarly sized limbed or finned organisms. These methods can be as efficient as legged locomotion (1) and moreover are particularly versatile when moving over uneven terrain or through narrow crevices, for which the possession of limbs would be an impediment (2, 3). Limbless invertebrates such as slugs propel themselves by generating lubrication forces with their mucus-covered bodies; earthworms move by ratcheting: propulsion is achieved by engaging their hairs in the ground as they elongate and shorten their bodies (4, 5). Terrestrial snakes propel themselves by using a variety of techniques, including slithering by lateral undulation of the body, rectilinear progression by unilateral contraction/extension of their belly, concertina-like motion by folding the body as the pleats of an accordion, and sidewinding motion by throwing the body into a series of helices. This report will focus on lateral undulation, whose utility to locomotion by snakes has been previously described on the basis of push points: Snakes slither by driving their flanks laterally against neighboring rocks and branches found along the ground (6-11). This key assumption has informed numerous theoretical analyses (12-17) and facilitated the design of snake robots for search-and-rescue operations. Previous investigators (7,9,18,19) have suggested that the frictional anisotropy of the snake's belly scales might play a role in locomotion over flat surfaces. The details of this frictionbased process, however, remain to be understood; consequently, snake robots have been generally built to slither over flat surfaces by using passive wheels fixed to the body that resist lateral motion (18,(20)(21)(22). In this report, we present a theory for how snakes slither, or how wheelless snake robots can be designed to slither, on relatively featureless terrain, such as sand or bare rock, ...

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mentioning

confidence: 99%

The mechanics of slithering locomotion

Nirody

Scott

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

347

421

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“…From a mechanistic perspective, lateral undulatory locomotion on land has its genesis in the interaction between retrograde flexural waves propagating along the slender body and anisotropic frictional contact with a solid environment. ¶ Although this has been known qualitatively for a long time (1,3,8,9), a number of questions remain. In particular, understanding the coupling of the endogenous dynamics of muscular force generation to the exogenous dynamics of the interaction of the organism with its external environment to determine the gait and velocity remains an open question.…”

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confidence: 99%

Limbless undulatory propulsion on land

Guo¹,

Mahadevan

2008

Proc. Natl. Acad. Sci. U.S.A.

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We analyze the lateral undulatory motion of a natural or artificial snake or other slender organism that ''swims'' on land by propagating retrograde flexural waves. The governing equations for the planar lateral undulation of a thin filament that interacts frictionally with its environment lead to an incomplete system. Closures accounting for the forces generated by the internal muscles and the interaction of the filament with its environment lead to a nonlinear boundary value problem, which we solve using a combination of analytical and numerical methods. We find that the primary determinant of the shape of the organism is its interaction with the external environment, whereas the speed of the organism is determined primarily by the internal muscular forces, consistent with prior qualitative observations. Our model also allows us to pose and solve a variety of optimization problems such as those associated with maximum speed and mechanical efficiency, thus defining the performance envelope of this mode of locomotion.undulatory locomotion ͉ optimization ͉ snake ͉ worm S lender organisms such as sperms, worms, snakes, and eels propel themselves through a fluid using undulatory waves of flexure that propagate along their body (1). However, undulatory propulsion is not limited to movements through a liquid. Indeed, the side-to-side slithering of snakes, worms, and other elongated organisms that ''swim'' on land by lateral undulation has piqued the curiosity and interest of humans since biblical times (2). § It is only in the last century that we have begun to understand this unusual (and seemingly inefficient) mode of locomotion (3). These studies continue into the present, as zoologists try to decipher the neural and physiological bases for the generation of rhythmic patterns of muscular contraction (4,5) and engineers build and analyze hyperredundant robotic machines inspired by these organisms (6, 7). From a mechanistic perspective, lateral undulatory locomotion on land has its genesis in the interaction between retrograde flexural waves propagating along the slender body and anisotropic frictional contact with a solid environment. ¶ Although this has been known qualitatively for a long time (1,3,8,9), a number of questions remain. In particular, understanding the coupling of the endogenous dynamics of muscular force generation to the exogenous dynamics of the interaction of the organism with its external environment to determine the gait and velocity remains an open question. Furthermore, the important aspects of locomotion associated with gait selection in the presence of sensorimotor feedback are not addressed. Lateral undulatory locomotion on land allows us to approach both these basic questions directly in the context of a relatively simple and realistic model for the exogenous dynamics, allowing the organism's gait, defined here as the periodic shape of the organism, its velocity, and the reactive forces on it to be determined simultaneously. In addition, the simplicity of the model allows us to explore th...

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“…Young et al [73] investigated the motion of bubble in a vertical temperature gradient against buoyancy forces. Kuznetsov et al [74] demonstrated that, in the case of high transverse temperature gradients, the trajectory of the rise of bubbles deviates from rectilinear.…”

Section: Thermocapillary Effects During the Motion Of Bubbles In Chanmentioning

confidence: 98%

“…The presence of significant temperature gradients in liquid likewise affects the motion of bubbles due to thermocapillary effects on their surface [73,74]. A variation of surface tension causes the emergence of the difference of Laplace pressures at opposite points of bubble; this causes the bubble to move toward higher temperatures at ∂σ/∂T < 0.…”

Section: Thermocapillary Effects During the Motion Of Bubbles In Chanmentioning

confidence: 98%

Two-phase flows in pipes and capillary channels

Chinnov

Kabov

2006

High Temp

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This review is devoted to analysis of two-phase flow patterns in capillary channels. Studies are considered in which flow pattern maps are obtained of two-phase flow in channels of different cross sections with the transverse dimension ranging from 20 μm to 255 mm. Data on flow patterns are systematized and given in tables. The impact made by capillary effects is analyzed compared to the influence of other factors under conditions of two-phase flow in channels. The classification of channels based on the degree of manifestation of capillarity is validated. Characteristic features of two-phase flow in channels of noncircular cross section are considered. It is demonstrated that thermocapillary effects may be significant under conditions of nonisothermal two-phase flow in microchannels and under conditions of weak effect of gravitation.CONTENTS

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On the motive mechanism of snakes and fish

Cited by 20 publications

References 0 publications

The mechanics of slithering locomotion

The mechanics of slithering locomotion

Limbless undulatory propulsion on land

Two-phase flows in pipes and capillary channels

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