The efficiency of propulsion by a rotating flagellum

Purcell, Edward M.

doi:10.1073/pnas.94.21.11307

Cited by 325 publications

(225 citation statements)

References 16 publications

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“…In the absence of inertia ͑Re→ 0͒, the equations of motion become time-reversible and any net movement attained by the swimmer must result from nonreciprocal motion. 1 Strategies for swimming at low Re include ͑i͒ rotation of a helical filament 2,3 and ͑ii͒ actuation of a flexible tail to generate propulsive forces. [4][5][6][7][8] The study of this latter mechanism has been motivated in part by early experimental observations of the propulsion of spermatozoa 9 and has been investigated using resistive force theory by Gray and Hancock.…”

Section: Introductionmentioning

confidence: 99%

Propulsive force measurements and flow behavior of undulatory swimmers at low Reynolds number

et al. 2010

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The swimming behavior of the nematode Caenorhabditis elegans is investigated in aqueous solutions of increasing viscosity. Detailed flow dynamics associated with the nematode's swimming motion as well as propulsive force and power are obtained using particle tracking and velocimetry methods. We find that C. elegans delivers propulsive thrusts on the order of a few nanonewtons. Such findings are supported by values obtained using resistive force theory; the ratio of normal to tangential drag coefficients is estimated to be approximately 1.4. Over the range of solutions investigated here, the flow properties remain largely independent of viscosity. Velocity magnitudes of the flow away from the nematode body decay rapidly within less than a body length and collapse onto a single master curve. Overall, our findings support that C. elegans is an attractive living model to study the coupling between small-scale propulsion and low Reynolds number hydrodynamics. The swimming behavior of the nematode Caenorhabditis elegans is investigated in aqueous solutions of increasing viscosity. Detailed flow dynamics associated with the nematode's swimming motion as well as propulsive force and power are obtained using particle tracking and velocimetry methods. We find that C. elegans delivers propulsive thrusts on the order of a few nanonewtons. Such findings are supported by values obtained using resistive force theory; the ratio of normal to tangential drag coefficients is estimated to be approximately 1.4. Over the range of solutions investigated here, the flow properties remain largely independent of viscosity. Velocity magnitudes of the flow away from the nematode body decay rapidly within less than a body length and collapse onto a single master curve. Overall, our findings support that C. elegans is an attractive living model to study the coupling between small-scale propulsion and low Reynolds number hydrodynamics. Disciplines Engineering | Mechanical Engineering

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Section: Introductionmentioning

confidence: 99%

Propulsive force measurements and flow behavior of undulatory swimmers at low Reynolds number

et al. 2010

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“…Other recent investigations are concerned with the motion and propulsion of cell and bacteria. 2,3 Microorganisms that undergo low-Reynolds-number swimming motions usually rely on propulsion mechanisms that break the time reversibility of the Stokes equations, such as rotating flagellas or flexible oars. 4 The effect of a nearby nonslip rigid wall on the motion of these micro-swimmers has been found to be important.…”

Section: Introductionmentioning

confidence: 99%

The elastohydrodynamic force on a sphere near a soft wall

2007

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The influence of soft boundaries on the forces experienced by a small sphere undergoing slow translation and rotation near a wall is investigated using asymptotic and numerical methods. The clearance between the sphere and the wall is assumed to be small, so that the lubrication approximation holds in the gap. The forces induced by boundary deformation break the symmetry of the Stokes equations, leading to irreversibility of the motion of the sphere and yielding a nonzero lift force. A general formulation, applicable to any constitutive equation of the wall, is presented, and an asymptotic analysis for slightly soft boundaries is developed and applied to a thin compressible elastic layer coating a rigid surface. Expressions are derived for the elastohydrodynamic lift exerted on a sphere moving parallel to the wall, which include the influence of the sphere rotation in the direction of its motion. The results extend and correct previous work, and are different from those for the elastohydrodynamic motion of a cylinder near a wall, in that the geometry eliminates the occurrence of maximum lift and optimum choice of the material properties of the boundary.

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“…A numerical model has been setup for this type of swimmer which gave the relation among the swimming velocity, efficiency, and external torque [56,57].…”

Section: Propulsion By Magnetic Fieldmentioning

confidence: 99%

Mini and Micro Propulsion for Medical Swimmers

Feng

Cho

2014

Micromachines

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Mini and micro robots, which can swim in an underwater environment, have drawn widespread research interests because of their potential applicability to the medical or biological fields, including delivery and transportation of bio-materials and drugs, bio-sensing, and bio-surgery. This paper reviews the recent ideas and developments of these types of self-propelling devices, ranging from the millimeter scale down to the micro and even the nano scale. Specifically, this review article makes an emphasis on various propulsion principles, including methods of utilizing smart actuators, external magnetic/electric/acoustic fields, bacteria, chemical reactions, etc. In addition, we compare the propelling speed range, directional control schemes, and advantages of the above principles.

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The efficiency of propulsion by a rotating flagellum

Cited by 325 publications

References 16 publications

Propulsive force measurements and flow behavior of undulatory swimmers at low Reynolds number

Propulsive force measurements and flow behavior of undulatory swimmers at low Reynolds number

The elastohydrodynamic force on a sphere near a soft wall

Mini and Micro Propulsion for Medical Swimmers

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