An experimental study of particle migration in pipe flow of viscoelastic fluids

Mohammad, Tehrani

doi:10.1122/1.550773

Cited by 108 publications

(100 citation statements)

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“…The lateral particle migration speed in a DNA solution depends upon the particle size a as denoted in equation (1) (Methods). This kind of behaviour was previously reported in synthetic polymer solutions 18,22,28,29 . We demonstrate a chromatographic separation of micron-sized particles utilizing this dependency of the lateral migration speed on particle size.…”

Section: Resultssupporting

confidence: 50%

“…Lateral particle migration speed under non-Newtonian flow was predicted using previous semiempirical approaches 18,20,22,29 . Specifically, the dilute DNA solutions used in this work are Boger fluids, which are non-Newtonian elastic fluids with constant shear viscosities as shown in Supplementary Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The dependency of Wi and the aspect ratio of particle size to channel height has been previously predicted 18,20,22,29 . The overlapping concentration c ?…”

Section: Polymer Contribution To the Viscosity Of A Polymer Solution mentioning

confidence: 99%

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DNA-based highly tunable particle focuser

et al. 2013

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DNA is distinguished by both long length and structural rigidity. Classical polymer theories predict that DNA enhances the non-Newtonian elastic properties of its dilute solution more significantly than common synthetic flexible polymers because of its larger size and longer relaxation time. Here we exploit this property to report that under Poiseuille microflow, rigid spherical particles laterally migrate and form a tightly focused stream in an extremely dilute DNA solution (0.0005 (w/v)%). By the use of the DNA solution, we achieve highly efficient focusing (499.5%) over an unprecedented wide range of flow rates (ratio of maximum to minimum flow rates B400). This highly tunable particle-focusing technique can be used in the design of cost-effective portable flow cytometers, high-throughput cell analysis and also for cell sorting by size. We demonstrate that DNA is an efficient elasticity enhancer, which originates from its unique structural properties.

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Section: Resultssupporting

confidence: 50%

Section: Methodsmentioning

confidence: 99%

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DNA-based highly tunable particle focuser

et al. 2013

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“…Under the assumption of zero Reynolds number and small blockage ratio, Ho & Leal (1976) showed that a lateral force, originating from the normal stress differences, drives the particle towards the lower-shear region in a second-order fluid. This conclusion has been verified in other experiments and simulations, where particles move to the central axis of a circular tube (Tehrani 1996;D'Avino et al 2012;Romeo et al 2013;Kang et al 2014) and to both centreline and corners in a rectangular channel (Yang et al 2011;Leshansky et al 2007). Based on simulations of the Giesekus and Phan Thien-Tanner constitutive equations, Villone et al (2011, 2013) and D'Avino et al (2012 observed bistable dynamics of particles in shear-thinning fluids, i.e.…”

Section: Introductionsupporting

confidence: 51%

“…For example, particles move towards the centreline in viscoelastic fluids of constant viscosity, whereas they move towards the walls in a shear-thinning fluid Gauthier et al 1971). Particles also move towards the centreline in solutions of moderately cross-linked polymers, whereas little or no migration is observed in solutions of highly cross-linked polymers (Tehrani 1996). Under the assumption of zero Reynolds number and small blockage ratio, Ho & Leal (1976) showed that a lateral force, originating from the normal stress differences, drives the particle towards the lower-shear region in a second-order fluid.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of particle migration in channel flow of viscoelastic fluids

2015

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The migration of a sphere in the pressure-driven channel flow of a viscoelastic fluid is studied numerically. The effects of inertia, elasticity, shear-thinning viscosity, secondary flows and the blockage ratio are considered by conducting fully resolved direct numerical simulations over a wide range of parameters. In a Newtonian fluid in the presence of inertial effects, the particle moves away from the channel centreline. The elastic effects, however, drive the particle towards the channel centreline. The equilibrium position depends on the interplay between the elastic and inertial effects. Particle focusing at the centreline occurs in flows with strong elasticity and weak inertia. Both shear-thinning effects and secondary flows tend to move the particle away from the channel centreline. The effect is more pronounced as inertia and elasticity effects increase. A scaling analysis is used to explain these different effects. Besides the particle migration, particle-induced fluid transport and particle migration during flow start-up are also considered. Inertia effects, shear-thinning behaviour, and secondary flows are all found to enhance the effective fluid transport normal to the flow direction. Due to the oscillation in fluid velocity and strong normal stress differences that develop during flow start-up, the particle has a larger transient migration velocity, which may be potentially used to accelerate the particle-focusing.

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