Cross-stream forces and velocities of fixed and freely suspended particles in viscoelastic Poiseuille flow: Perturbation and numerical analyses

Lee, Eric F.; Koch, Donald L.; Joo, Yong Lak

doi:10.1016/j.jnnfm.2010.06.014

Cited by 18 publications

(8 citation statements)

References 16 publications

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“…The migration behavior of particles is thus determined by the competing effects of fluid shear thinning and elasticity (Re ≪ 1). When shear thinning is excessively strong, particles migrate to the channel wall only; conversely, particles migrate to the channel centerline if elasticity is dominant 47,69 , such as in Boger fluids (elastic with constant viscosity) 92 . Sometimes, the term separatrix is employed to describe such competing effects on particle migration 47,93 .…”

Section: Newtonian Fluidmentioning

confidence: 99%

“…Apart from mixing with water, these macromolecules are also commonly mixed into glycerol−water medium, which increases viscosity and thus reduces the Reynolds number (see Box PEO M w = 2 × 10 6 g/mol; PVP M w = 3.6 × 10 5 g/mol; PAA M w = 18 × 10 6 g/mol (e.g., De > 2.5) 49,52 . The competition between shear thinning and fluid elasticity leads to an unstable separatrix between the channel centerline and wall 47,92 . With negligible inertia, particles initially located between the separatrix and channel wall migrate toward and equilibrate near the wall; particles on the other side of the separatrix are focused into the centerline.…”

Section: Box 4 Common Macromolecules Used As Elasticity Enhancersmentioning

confidence: 99%

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Viscoelastic microfluidics: progress and challenges

2020

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The manipulation of cells and particles suspended in viscoelastic fluids in microchannels has drawn increasing attention, in part due to the ability for single-stream three-dimensional focusing in simple channel geometries. Improvement in the understanding of non-Newtonian effects on particle dynamics has led to expanding exploration of focusing and sorting particles and cells using viscoelastic microfluidics. Multiple factors, such as the driving forces arising from fluid elasticity and inertia, the effect of fluid rheology, the physical properties of particles and cells, and channel geometry, actively interact and compete together to govern the intricate migration behavior of particles and cells in microchannels. Here, we review the viscoelastic fluid physics and the hydrodynamic forces in such flows and identify three pairs of competing forces/effects that collectively govern viscoelastic migration. We discuss migration dynamics, focusing positions, numerical simulations, and recent progress in viscoelastic microfluidic applications as well as the remaining challenges. Finally, we hope that an improved understanding of viscoelastic flows in microfluidics can lead to increased sophistication of microfluidic platforms in clinical diagnostics and biomedical research.

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Section: Newtonian Fluidmentioning

confidence: 99%

Section: Box 4 Common Macromolecules Used As Elasticity Enhancersmentioning

confidence: 99%

Viscoelastic microfluidics: progress and challenges

2020

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“…28 Ho and Leal predicted that a particle laterally migrates in second-order fluid by an imbalanced first or second normal stress difference. 19 Lateral particle migration in viscoelastic fluids has also been predicted with computational simulations based on nonlinear constitutive modeling such as Oldroyd-B and Gisekus models [29][30][31][32][33][34] or molecular dynamics. 35 The equilibrium particle positions in a viscoelastic channel flow are determined by various factors such as the rheological properties of the suspending medium, and the competition between inertial and elastic forces if the Reynolds number is non-negligible.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Elasto-inertial particle focusing under the viscoelastic flow of DNA solution in a square channel

Kim

2016

Biomicrofluidics

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Particle focusing is an essential step in a wide range of applications such as cell counting and sorting. Recently, viscoelastic particle focusing, which exploits the spatially non-uniform viscoelastic properties of a polymer solution under Poiseuille flow, has attracted much attention because the particles are focused along the channel centerline without any external force. Lateral particle migration in polymer solutions in square channels has been studied due to its practical importance in labon-a-chip applications. However, there are still many questions about how the rheological properties of the medium alter the equilibrium particle positions and about the flow rate ranges for particle focusing. In this study, we investigated lateral particle migration in a viscoelastic flow of DNA solution in a square microchannel. The elastic property is relevant due to the long relaxation time of a DNA molecule, even when the DNA concentration is extremely low. Further, the shear viscosity of the solution is essentially constant irrespective of shear rate. Our current results demonstrate that the particles migrate toward the channel centerline and the four corners of a square channel in the dilute DNA solution when the inertia is negligible (elasticity-dominant flow). As the flow rate increases, the multiple equilibrium particle positions are reduced to a single file along the channel centerline, due to the elasto-inertial particle focusing mechanism. The current results support that elasto-inertial particle focusing mechanism is a universal phenomenon in a viscoelastic fluid with constant shear viscosity (Boger fluid). Also, the effective flow rate ranges for three-dimensional particle focusing in the DNA solution were significantly higher and wider than those for the previous synthetic polymer solution case, which facilitates high throughput analysis of particulate systems. In addition, we demonstrated that the DNA solution can be applied to focus a wide range of particle sizes in a single channel and also align red blood cells without any significant deformation. V

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“…In conclusion, the current study analyzes microswimmers in weakly viscoelastic pressure-driven flows. For neutral and pusher/puller microswimmers, we derive an additional swimming lift velocity depending on the swimmer's hydrodynamic signature that adds to the passive viscoelastic lift 33,41,60,61 . For source-dipole (neutral) swimmers, the swimming lift is two orders of magnitude stronger than the passive lift, which was considered alone in a recent study 33 .…”

Section: Typementioning

confidence: 99%