Propulsion of axisymmetric swimmers in viscoelastic liquids by means of torsional oscillations

Böhme, Gert; Müller, A.

doi:10.1016/j.jnnfm.2015.07.010

Cited by 5 publications

(5 citation statements)

References 19 publications

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“…Keim et al [35] then demonstrated experimentally this elasticity enabled locomotion for a rigid assembly of two connected spheres undergoing rotational oscillations about an axis perpendicular to their mutual axis of symmetry. Böhme and M üller [36] observed the same for axisymmetric swimmers performing reciprocal torsional oscillations. Pak et al [37] modelled a snowman swimmer, which has two unequal spheres that rotate about their common axis, that can swim only in complex fluids.…”

Section: Introductionmentioning

confidence: 64%

Two-sphere swimmers in viscoelastic fluids

2018

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We examine swimmers comprising of two rigid spheres which oscillate periodically along their axis of symmetry, considering both when the oscillation is in phase and anti-phase, and study the effects of fluid viscoelasticity on their net motion. These swimmers both display reciprocal motion in a Newtonian fluid and hence no net swimming is achieved over one cycle. Conversely, we find that when the two spheres are of different sizes, the effect of viscoelasticity acts to propel the swimmers forward in the direction of the smaller sphere. Finally, we compare the motion of rigid spheres oscillating in viscoelastic fluids with elastic spheres in Newtonian fluids where we find similar results. * Electronic mail: gelfring@mech.ubc.ca arXiv:1809.04268v1 [physics.flu-dyn]

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Section: Introductionmentioning

confidence: 64%

Two-sphere swimmers in viscoelastic fluids

2018

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“…This has also been accompanied by numerous theoretical studies (e.g. Krieger et al (2015); Boehme & Mueller (2015); Riley & Lauga (2015); Elfring & Goyal (2016)), numerical investigations (e.g. Thomases & Guy (2014); Salazar et al (2016)) and experimental explorations (e.g.…”

Section: Introductionmentioning

confidence: 93%

Boundary element methods for particles and microswimmers in a linear viscoelastic fluid

Ishimoto

Gaffney

2017

J. Fluid Mech.

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The consideration of viscoelasticity within fluid dynamical boundary element methods has traditionally required meshing over the whole flow domain. In turn, a major advantage of the boundary element method is lost, namely the need to consider only surface boundary integrals. Here, using a generalised reciprocal relation and viscoelastic force singularities, a boundary element method is developed for linear viscoelastic flows. We proceed to explore finite-deformation microswimming in a linear Maxwell fluid. We firstly deduce a finite-amplitude generalisation of a previously reported result that the flow field is unchanged between a Newtonian and linear Maxwell fluid for prescribed small-amplitude deformations. Hence Purcell’s theorem holds for a linear Maxwell fluid. We proceed to consider deformation swimming in a linear Maxwell fluid given an external forcing. Boundary scattering trajectories for an exemplar squirmer approaching a surface are observed to exhibit a weak dependence on the Deborah number, while the trajectories of a sperm and monotrichous bacterium near a surface are predicted to be essentially unaffected at moderate Deborah number. In turn, the latter supports the common simplification of using Newtonian Stokes flows for studying flagellate swimming in linear Maxwell media. In addition, the motion of a magnetic helix under the influence of an external magnetic field is considered, and highlights that linear viscoelasticity can significantly impact the propagation of the helix, in turn demonstrating that even linear rheology is important to consider for forced swimmers. Finally, the presented framework requires minimalistic adjustments to Newtonian boundary element codes, enabling rapid implementation, and is more generally applicable, for instance to studies of particle interactions in active linear rheology on the microscale.

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“…They showed that by using the solution to the auxiliary rigid-body resistance problem one may solve for the swimming kinematics of a deforming body without resolving the flow field it generates. Lauga later extended the use of the reciprocal theorem for swimming to non-Newtonian fluids 14 and these ideas were then subsequently further developed 23,43 and integral theorems have subsequently been used in a number of recent theoretical studies of locomotion in complex fluids 21,24,28,29,51 . We present here integral theory for a general non-Newtonian fluid in the formalism of Elfring and Lauga 43 before showing its application to simple bodies.…”

Section: The Complex Reciprocal Theoremmentioning

confidence: 99%

“…Several recent articles have investigated changes in swimming kinematics due to nonlinear viscoelasticity theoretically 14,[17][18][19][20][21][22][23][24][25][26][27][28][29][30] , numerically [31][32][33][34][35][36] and experimentally [37][38][39][40][41][42] , while comprehensive reviews have summarized key findings in the theory 43 , and experiments 44 , of biolocomotion in complex fluids. The picture that emerges from recent studies on the effects of viscoelastic fluids, is that whether a swimmer goes faster or slower depends on the type of gait 31,34 or the amplitude of the gait 33,37 .…”

Section: Introductionmentioning

confidence: 99%

The effect of gait on swimming in viscoelastic fluids

Elfring

Goyal

2016

Journal of Non-Newtonian Fluid Mechanics

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In this paper, we give formulas for the swimming of simplified two-dimensional bodies in complex fluids using the reciprocal theorem. By way of these formulas we calculate the swimming velocity due to small-amplitude deformations on the simplest of these bodies, a two-dimensional sheet, to explore general conditions on the swimming gait under which the sheet may move faster, or slower, in a viscoelastic fluid compared to a Newtonian fluid. We show that in general, for small amplitude deformations, a speed increase can only be realized by multiple deformation modes in contrast to slip flows. Additionally, we show that a change in swimming speed is directly due to a change in thrust generated by the swimmer.

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Propulsion of axisymmetric swimmers in viscoelastic liquids by means of torsional oscillations

Cited by 5 publications

References 19 publications

Two-sphere swimmers in viscoelastic fluids

Two-sphere swimmers in viscoelastic fluids

Boundary element methods for particles and microswimmers in a linear viscoelastic fluid

The effect of gait on swimming in viscoelastic fluids

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