Force moments of an active particle in a complex fluid

Elfring, Gwynn J.

doi:10.1017/jfm.2017.632

Cited by 36 publications

(48 citation statements)

References 36 publications

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“…where U = [U Ω] is six-dimensional vector comprising rigid-body translational and rotational velocities respectively (we use bold sans serif fonts for six-dimensional vectors and tensors and bold serif for three dimensional ones) [43,44]. The six-dimensional vector F ext = [F ext L ext ] contains any external force and torque acting on the swimmer.…”

Section: B Theory For Swimming In Complex Fluidsmentioning

confidence: 99%

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: B Theory For Swimming In Complex Fluidsmentioning

confidence: 99%

Two-sphere swimmers in viscoelastic fluids

2018

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“…where U = [U Ω] is a 6-dimensional vectors containing translational and rotational velocities, likewise F = [F L] represents both force and torque [47]. We consider here a particle that is neutrally buoyant and that no other external force acts on the particle and thus F ext = 0.…”

Section: B Shear-thinning Fluidsmentioning

confidence: 99%

“…We may write for simplicity that velocity is composed of a Newtonian part and a non-Newtonian correction U = U 0 +R −1 F U · F N N . A similar approach has also been used for studying the dynamics of active particles in complex fluids [47][48][49].…”

Section: B Shear-thinning Fluidsmentioning

confidence: 99%

Jeffery orbits in shear-thinning fluids

Abtahi

Elfring

2019

Physics of Fluids

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We investigate the dynamics of a prolate spheroid in a shear flow of a shear-thinning Carreau fluid. The motion of a prolate particle is developed analytically for asymptotically weak shear thinning and then integrated numerically. We find that shear-thinning rheology does not lift the degeneracy of Jeffery orbits observed in Newtonian fluids but the instantaneous rate of rotation and trajectories of the orbits are modified. Qualitatively, shear thinning has a similar effect to elongating the particle in a Newtonian fluid. The period of rotation increases as the particle slows down more when aligned with the flow due to a reduction of shear stresses. Unlike Jeffery orbits in Newtonian fluids, in shear-thinning fluids the period of orbits depends on the specific trajectory (or initial orientation of the particle). * gelfring@mech.ubc.ca arXiv:1908.08687v2 [physics.flu-dyn]

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“…Besides, an active particle (AP) in a viscoelastic fluid represents an example of a random walker in a nonequilibrium thermal bath, being of fundamental relevance for non-equilibrium statistical physics [21]. Despite holding such immense potential, theoretical studies involving the dynamics of self-propelled particles in complex fluids are rather scarce [22][23][24][25][26][27][28][29][30][31]. Experiments dealing with artificial microswimmers in viscoelastic fluids, demonstrate remarkable differences compared to entirely viscous environments [32,33].…”

Section: Introductionmentioning

confidence: 99%

Active particles in geometrically confined viscoelastic fluids

2019

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We experimentally study the dynamics of active particles (APs) in a viscoelastic fluid under various geometrical constraints such as flat walls, spherical obstacles and cylindrical cavities. We observe that the main effect of the confined viscoelastic fluid is to induce an effective repulsion on the APs when moving close to a rigid surface, which depends on the incident angle, the surface curvature and the particle activity. Additionally, the geometrical confinement imposes an asymmetry to their movement, which leads to strong hydrodynamic torques, thus resulting in detention times on the wall surface orders of magnitude shorter than suggested by thermal diffusion. We show that such viscoelasticity-mediated interactions have striking consequences on the behavior of multi-AP systems strongly confined in a circular pore. In particular, these systems exhibit a transition from liquid-like behavior to a highly ordered state upon increasing their activity. A further increase in activity melts the order, thus leading to a re-entrant liquid-like behavior.

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Force moments of an active particle in a complex fluid

Cited by 36 publications

References 36 publications

Two-sphere swimmers in viscoelastic fluids

Two-sphere swimmers in viscoelastic fluids

Jeffery orbits in shear-thinning fluids

Active particles in geometrically confined viscoelastic fluids

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