Migration of a sphere in tube flow

Yang, Bo; Wang, Jing; Joseph, Daniel D.; Hu, Hsou Mei; Pan, Tsorng‐Whay; Glowinski, Roland

doi:10.1017/s0022112005005677

Cited by 128 publications

(117 citation statements)

References 26 publications

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“…In a tube flow, initially randomly distributed particles gradually focus into a narrow annulus at around 0.3 diameter, resulting in the "tubular pinch" effect. This phenomenon was later confirmed in several experimental Matas et al 2004) and analytical (Schonberg & Hinch 1989) and numerical (Feng et al 1994;Yang et al 2005) studies. Similar phenomenon occurs in square-and rectangular-shaped channels, where particles accumulate at 0.3 times the width of the channel away from the centreline (Chun & Ladd 2006;Kim & Yoo 2008;Shao et al 2008;Choi et al 2011).…”

Section: Introductionmentioning

confidence: 54%

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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Section: Introductionmentioning

confidence: 54%

Dynamics of particle migration in channel flow of viscoelastic fluids

2015

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“…All cases are found to yield a solid-solid clash within a finite scaled time. This can be contrasted and compared with the interesting findings of Yih [34], Korobkin [35], Korobkin & Ohkusu [36], Schonberg & Hinch [19], Newman [37], Tuck [38], Fortes et al [39], Huang et al [40], Yang et al [41] and Ardekani et al [42]. The typical present clash occurs mid-body instead of at the leading edge as in Smith & Ellis [32] and this new form is examined in detail in § §3 and 4.…”

Section: Introductionmentioning

confidence: 82%

Fluid–body interactions: clashing, skimming, bouncing

Smith

Wilson

2011

Phil. Trans. R. Soc. A.

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Solid-solid and solid-fluid impacts and bouncing are the concern here. A theoretical study is presented on fluid-body interaction in which the motion of the body and the fluid influence each other nonlinearly. There could also be many bodies involved. The clashing refers to solid-solid impacts arising from fluid-body interaction in a channel, while the skimming refers to another area where a thin body impacts obliquely upon a fluid surface. Bouncing usually then follows in both areas. The main new contribution concerns the influences of thickness and camber which lead to a different and more general form of clashing and hence bouncing.

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“…The lift coefficient is zero at the centerline and is called an unstable equilibrium position. 42 Because the gradient of the force is non-zero, a small disturbance can drive a droplet away from the centerline and toward the wall. Interestingly, the stable zero-lift positions for the two velocity profiles coincide at the same scaled position y/W = 0.3.…”

Section: Theoretical Analysis a Lift Forcementioning

confidence: 99%

Inertial migration of deformable droplets in a microchannel

Chen

Xue

Zhang³

et al. 2014

Physics of Fluids

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The microfluidic inertial effect is an effective way of focusing and sorting droplets suspended in a carrier fluid in microchannels. To understand the flow dynamics of microscale droplet migration, we conduct numerical simulations on the droplet motion and deformation in a straight microchannel. The results are compared with preliminary experiments and theoretical analysis. In contrast to most existing literature, the present simulations are three-dimensional and full length in the streamwise direction and consider the confinement effects for a rectangular cross section. To thoroughly examine the effect of the velocity distribution, the release positions of single droplets are varied in a quarter of the channel cross section based on the geometrical symmetries. The migration dynamics and equilibrium positions of the droplets are obtained for different fluid velocities and droplet sizes. Droplets with diameters larger than half of the channel height migrate to the centerline in the height direction and two equilibrium positions are observed between the centerline and the wall in the width direction. In addition to the well-known Segré-Silberberg equilibrium positions, new equilibrium positions closer to the centerline are observed. This finding is validated by preliminary experiments that are designed to introduce droplets at different initial lateral positions. Small droplets also migrate to two equilibrium positions in the quarter of the channel cross section, but the coordinates in the width direction are between the centerline and the wall. The equilibrium positions move toward the centerlines with increasing Reynolds number due to increasing deformations of the droplets. The distributions of the lift forces, angular velocities, and the deformation parameters of droplets along the two confinement direction are investigated in detail. Comparisons are made with theoretical predictions to determine the fundamentals of droplet migration in microchannels. In addition, existence of the inner equilibrium position is linked to the quartic velocity distribution in the width direction through a simple model for the slip angular velocities of droplets.

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Migration of a sphere in tube flow

Cited by 128 publications

References 26 publications

Dynamics of particle migration in channel flow of viscoelastic fluids

Dynamics of particle migration in channel flow of viscoelastic fluids

Fluid–body interactions: clashing, skimming, bouncing

Inertial migration of deformable droplets in a microchannel

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