Inertial effects in small-amplitude swimming of a finite body

Felderhof, B. U.; Jones, Robert B.

doi:10.1016/0378-4371(94)90169-4

Cited by 44 publications

(75 citation statements)

References 19 publications

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“…In general, in order to use the reciprocal formulation one must know the solution to the auxiliary problemσ for all S(t), which is typically impractical for a nontrivial gait. When S(t) deviates only slightly from S 0 we can, through Taylor series expansions, recast the problem onto S 0 [16,17]. As the shape of S 0 is invariant in time we then need only the resolution of a single auxiliary problem.…”

Section: The Scallop Theoremmentioning

confidence: 99%

Theory of Locomotion Through Complex Fluids

Elfring

Lauga

2014

Complex Fluids in Biological Systems

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Microorganisms such as bacteria often swim in fluid environments that cannot be classified as Newtonian. Many biological fluids contain polymers or other heterogeneities which may yield complex rheology. For a given set of boundary conditions on a moving organism, flows can be substantially different in complex fluids, while non-Newtonian stresses can alter the gait of the microorganisms themselves. Heterogeneities in the fluid may also be characterized by length scales on the order of the organism itself leading to additional dynamic complexity. In this chapter we present a theoretical overview of small-scale locomotion in complex fluids with a focus on recent efforts quantifying the impact of non-Newtonian rheology on swimming microorganisms.

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Section: The Scallop Theoremmentioning

confidence: 99%

Theory of Locomotion Through Complex Fluids

Elfring

Lauga

2014

Complex Fluids in Biological Systems

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“…As the Stokesian regime is characterized by the absence of time in the flow equations, the description of self-propulsion reduces to a purely geometrical problem of transformation of the microswimmer's body shape. The problem was solved for various nearly spherical objects, whose surface is deformed by a wave-like perturbation in the manner of ciliated microorganisms [3,4,5,6,7]. A number of other simple models performing one-or two-dimensional non-reciprocal moves as well as their swimming performance were discussed recently [8,9,10].…”

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confidence: 99%

Brownian dynamics of a microswimmer

Lobaskin

Lobaskin²,

Kulić

2008

Eur. Phys. J. Spec. Top.

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We report on dynamic properties of a simple model microswimmer composed of three spheres and propelling itself in a viscous fluid by spinning motion of the spheres under zero net torque constraint. At a fixed temperature and increasing the spinning frequency, the swimmer demonstrates a transition from dissipation-dominated to a pumping-dominated motion regime characterized by negative effective friction coefficient. In the limit of high frequencies, the diffusion of the swimmer can be described by a model of an active particle with constant velocity.Attention of physics community to the problem of swimming at low Reynolds numbers, which is relevant for the world of microorganisms, was attracted by Edward Purcell in seventies [1]. He formulated the basic principles of self-propulsion and suggested a variety of simple model microswimmers that would propel themselves in the Stokesian regime using non-reciprocal cyclic moves. The most famous of them, three-link swimmer, was solved analytically only recently [2]. As the Stokesian regime is characterized by the absence of time in the flow equations, the description of self-propulsion reduces to a purely geometrical problem of transformation of the microswimmer's body shape. The problem was solved for various nearly spherical objects, whose surface is deformed by a wave-like perturbation in the manner of ciliated microorganisms [3,4,5,6,7]. A number of other simple models performing one-or two-dimensional non-reciprocal moves as well as their swimming performance were discussed recently [8,9,10].Recent advances in micromanipulation techniques made it possible to construct artificial swimmers mimicking the bacterial and protozoal self-propulsion mechanisms. Most of these machines, however, are supposed to be driven by an external fields rather than ATP hydrolysis. The first working device imitating the flagellum beating and driven by an external magnetic field was reported recently [11]. Realistic implementations of DNA-based nanomachines using the ratchet principle were also suggested [12,13]. Other directions in development of self-propelling micromachines is related to use of anisotropic environments, active surfaces or chemical reactions, whose mechanical response has an inherent asymmetry [14,15,16,17,18,19]. The focus of these publications is the propulsion mechanism as such and the dynamics of a swimmer on long timescales is usually not addressed. One should note, however, that on the nanometer and micrometer scale the thermal fluctuations are expected to compete with the propulsion mechanisms and, therefore, the interplay between the swimming and dissipation processes is of great interest [21,22,23,24,25,26]. In this work, we report on general dynamic properties of a microswimmer at finite temperatures.For our study we chose a simple model swimmer, consisting of three spheres with their centers comprising an equilateral triangle. The distances between the spheres are fixed. To impose propulsion, we make the spheres spin via applied constant torque. We arrange th...

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“…[4] Actually within a strict definition, directional swimming may be regarded as a forward motion by shape deformation. [5,6] For the sake of clarity we will use the term "morphing microswimmer" here for locomotion by shape deformation. In contrast to a macroscopic swimmer, such locomotion of small, lightweight microorganisms must take account of the fact that it takes place at very small Reynolds numbers, R e ≈ 10 .…”

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Soft Microrobots Employing Nonequilibrium Actuation via Plasmonic Heating

et al. 2016

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A soft microrobot composed of a microgel and driven by the light‐controlled nonequilibrium dynamics of volume changes is presented. The photothermal response of the microgel, containing plasmonic gold nanorods, enables fast heating/cooling dynamics. Mastering the nonequilibrium response provides control of the complex motion, which goes beyond what has been so far reported for hydrophilic microgels.

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Inertial effects in small-amplitude swimming of a finite body

Cited by 44 publications

References 19 publications

Theory of Locomotion Through Complex Fluids

Theory of Locomotion Through Complex Fluids

Brownian dynamics of a microswimmer

Soft Microrobots Employing Nonequilibrium Actuation via Plasmonic Heating

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