Inertial migration of a sphere in Poiseuille flow

Schonberg, Jeffrey A.; Hinch, E. J.

doi:10.1017/s0022112089001564

Cited by 324 publications

(345 citation statements)

References 6 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: 55%

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: 55%

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%

“…The industrial applications are manifold including in particular ship slamming, sloshing and granular flows on chutes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. There is also a huge number of biomedical applications [21][22][23][24][25][26][27][28][29][30][31], while sports applications are such as in skeleton bobsleigh.…”

Section: Introductionmentioning

confidence: 99%

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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“…6). In the fluid dynamical regime of bacteria, mechanisms including inertia, buoyancy and deformation that otherwise lead to the accumulation of particles 25 , bubbles 26 or red blood cells 27 , are insignificant or exceedingly slow (Supplementary Information). Instead, shearinduced trapping occurs as a result of self-propulsion, which drives cell accumulations within a timescale governed by the swimming speed and the flow length scale.…”

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confidence: 99%

Bacterial transport suppressed by fluid shear

2014

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Bacteria often live in dynamic fluid environments 1-3 and flow can a ect fundamental microbial processes such as nutrient uptake 1,4 and infection 5 . However, little is known about the consequences of the forces and torques associated with fluid flow on bacteria. Through microfluidic experiments, we show that fluid shear produces strong spatial heterogeneity in suspensions of motile bacteria, characterized by up to 70% cell depletion from low-shear regions due to 'trapping' in high-shear regions. Two mathematical models and a scaling analysis accurately capture these observations, including the maximal depletion at mean shear rates of 2.5-10 s −1 , and reveal that trapping by shear originates from the competition between the cell alignment with the flow and the stochasticity in the swimming orientation. We show that this shear-induced trapping directly impacts widespread bacterial behaviours, by hampering chemotaxis and promoting surface attachment. These results suggest that the hydrodynamic environment may directly a ect bacterial fitness and should be carefully considered in the study of microbial processes.We investigated the effect of flow on motile bacteria by tracking them in precisely controlled laminar flows generated in a microfluidic channel (Fig. 1a). To ensure that the dominant velocity gradients occurred in the horizontal observation plane, at the channel mid-depth, we used a microchannel with aspect ratio H /W > 1 (height H = 750 µm; width W = 425 µm). In that plane, the velocity profile, u(y) = U [1 − 4(y/W ) 2 ], where U is the flow velocity at the channel centreline, is parabolic, and, thus, the shear rate S(y) = du/dy = −8yU /W 2 varies linearly with distance y across the channel and is zero at the centreline (Fig. 1b). In this flow, smooth-swimming Bacillus subtilis bacteria swam unperturbed in straight paths (Fig. 1c) when near the centre of the channel, where the local shear rate was small. Conversely, in high-shear-rate regions, trajectories exhibited frequent loops resulting from rotation of the swimming bacteria by the hydrodynamic torque imparted by the local shear (Fig. 1d). The opposite handedness of the loops on either side of the channel centreline reflects the opposite sign of the shear rate (Fig. 1c,d and Supplementary Movie 1). As shown below, these looping trajectories resulted in bacteria becoming trapped in the high-shear region of the channel.At the population scale, this trapping effect resulted in a marked depletion of cells from the central, low-shear region of the flow, and consequently, in an accumulation in the flanking regions of higher shear. When the flow was impulsively started from rest, the initially uniform distribution of cells over the imaging region across the channel width (Fig. 1e) rapidly (5-10 s) evolved into a distribution characterized by considerably fewer cells in the central part of the channel (Fig. 1f-h). The magnitude of the depletion was severe, with local cell concentrations dropping by 70% (Fig. 1h). The absence of depletion in control experime...

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Inertial migration of a sphere in Poiseuille flow

Cited by 324 publications

References 6 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

Bacterial transport suppressed by fluid shear

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