Formation of liquid–liquid slug flow in a microfluidic T‐junction: Effects of fluid properties and leakage flow

Yao, Chaoqun; Liu, Yanyan; Xu, Chang; Zhao, Shuainan; Chen, Guangwen

doi:10.1002/aic.15889

Cited by 65 publications

(47 citation statements)

References 48 publications

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“…13b, the film thickness is still relatively thick in the plane of the longer semi-axis. When the inertia of the aqueous phase increases, the interface might become arcshaped in the plane of the longer semi-axis, with an even larger gap for film flow of the aqueous phase [31]. Such a large aqueous leakage flow around the organic core thread in rectangular and quasi-trapezoidal microchannels of high aspect ratios is very favorable for the persistence of tubing/threading in the cross-junction and annular flow in the downstream channel.…”

Section: Flow Patterns In the Main Microchannelmentioning

confidence: 99%

Liquid-liquid two-phase flow patterns in ultra-shallow straight and serpentine microchannels

Sundén

2018

Heat Mass Transfer

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Water-butanol and water-hexane flows were visualized in ultra-shallow straight and serpentine microchannels with a crossjunction. At the inlet cross-junction, three major flow patterns including tubing/threading, dripping and jetting were mapped using the aqueous Capillary number versus the organic Weber number. Correspondingly, in the main microchannel, annular flow, slug flow and droplet flow were mapped using combined dimensionless numbers (Weber number times Ohnesorge number) of both phases. The flow pattern transitions were explained based on a force analysis, considering the phase flow rates, junction angle between the side feeding channels and the central feeding channel as well as aspect ratios. Compared to the straight microchannel, the dripping regime at the inlet junction and the slug flow occupy larger zones in serpentine microchannels because the centrifugal force tends to break up the organic annular core into slugs and droplets over the bends. Nomenclature Bo Bond number, (ρ a-ρ o)gd h 2 /γ Ca Capillary number, μu/γ Ce A dimensionless number representing the ratio of centrifugal to interfacial forces, ρu 2 d h 2 /(γR) d Channel diameter, μm d h Hydraulic diameter, μm g Gravitational acceleration, m/s 2 h Channel depth, μm j Superficial velocity, m/s L Channel length, m Oh Ohnesorge number, μ/(d h ργ) 0.5 Q Volumetric flow rate, ml/h q Flow rate ratio of organic to aqueous phases R Bending curvature radius of the channel centerline, m Re Reynolds number, ρjd h /μ u Average velocity (the overall volumetric flow rate of the two phases divided by the cross-sectional area), m/s w Channel width, μm We Weber number, ρj 2 d h /γ Greek symbols γ Interfacial tension, N/m μ Dynamic viscosity, Pa•s ρ Density, kg/m 3 Subscript ave Average a Aqueous phase c Continuous phase d Dispersed phase o Organic phase

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Section: Flow Patterns In the Main Microchannelmentioning

confidence: 99%

Liquid-liquid two-phase flow patterns in ultra-shallow straight and serpentine microchannels

Sundén

2018

Heat Mass Transfer

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“…42 In the same range of Ca Á ϕ, the master curve fitted to own experimental data shows 17 % > Ca Á ϕ > 5% for the emerging droplet. The portion of continuous phase bypassing the droplet is lower by approximately a factor of two for the circular channel tested in this work compared to the rectangular channel tested by Yao et al, 42 The analysis of the effect of capillary number and volume flow rate ratio on the volume of the resulting droplet showed that the final droplet increases with flow rate ratio and decreases with the capillary number. This suggests that the leaking regime as presented by Korczyk et al 18 also applies for the co-flow configuration used in this work.…”

Section: Scanning Protocol and Postprocessingmentioning

confidence: 86%

“…A comparison of data presented by Yao et al 42 to own experimental results revealed that the proportion of continuous phase that bypasses the droplet is approximately reduced by a factor of two, F I G U R E 9 Summary of experimental results in terms ofη = f…”

Section: Scanning Protocol and Postprocessingmentioning

confidence: 91%

“…Even in the necking stage, a non-negligible portion of the continuous phase bypasses the emerging droplet/bubble. 41,42,40 Recently, Korczyk et al 18 published a mathematical model taking into account the flow around the droplet in the necking stage. In the model, the flow rate of the continuous phase is divided into a proportion bypassing the emerging droplet _ V b and a proportion contributing to the necking of the droplet _ V n .…”

Section: Introductionmentioning

confidence: 99%

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Micro‐computed tomography for the 3D time‐resolved investigation of monodisperse droplet generation in a co‐flow setup

et al. 2020

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Droplet generation in microfluidic devices has emerged as a promising approach for the design of highly controllable processes in the chemical and pharmaceutical industry. However, droplet generation is still not fully understood due to the complexity of the underlying physics. In this work, micro-computed tomography is applied to investigate droplet formation in a circular channel in a co-flow configuration at different flow conditions (Ca < 0.001). The application of an in-house developed scanning protocol assisted by comprehensive image processing allows for the time-resolved investigation of droplet formation. By tracking different droplet parameters (length, radii, volume, surface, Laplace pressure) the effect of flow conditions on droplet progression is determined. As characteristic for the squeezing regime, final droplet size was nearly independent of Ca for higher Ca tested. For lower Ca, the final droplet size increased with decreasing Ca, which points to the leaking regime that was recently introduced in the literature.

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“…Polymeric microfluidics have diverse applications that cover a wide area including particle and fluid manipulations. [1][2][3][4][5] Microfluidic paperbased analytical devices (μPADs), at first, were introduced for biological assay. 6 However, recently numerous applications other than biological assay including mixing, fuel cells and cell separation have been introduced for μPADs, [7][8][9] making papers a suitable alternative for polymeric materials.…”

Section: Introductionmentioning

confidence: 99%

A comparison of different geometrical elements to model fluid wicking in paper‐based microfluidic devices

Boodaghi

Shamloo

2019

AIChE Journal

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Recently, microfluidic paper-based analytical devices (μPADs) have outstripped polymeric microfluidic devices in the ease of fabrication and simplicity. Surface tension-based fluid motion in the paper's porous structure has made the paper a suitable substrate for multiple biological assays by directing fluid into multiple assay zones. The widespread assumption in most works for modeling wicking in a paper is that the paper is a combination of capillaries with the same diameter equal to the effective pore diameter. Although assuming paper as a bundle of capillaries gives a good insight into pressure force that drives the fluid inside the paper, there are some difficulties using the effective pore radius. The effective pore radius is totally different from the average geometrical pore radius which makes it impossible to predict wicking in μPADs based on geometrical parameters. In this article, we introduce different analytical and numerical models to investigate the possibility of determining the permeability of the paper, based on geometrical parameters rather than effective parameters. The lattice Boltzmann method is used for numerical simulations. The permeability of each of the proposed models was compared with the experimental permeability. Results indicated that assuming paper as a combination of capillaries and annuluses leads to accurate results that totally depend on average geometrical values rather than effective values. This paves the way for prediction of the fluid wicking only by considering average geometrical pore and fiber diameters.

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Formation of liquid–liquid slug flow in a microfluidic T‐junction: Effects of fluid properties and leakage flow

Cited by 65 publications

References 48 publications

Liquid-liquid two-phase flow patterns in ultra-shallow straight and serpentine microchannels

Liquid-liquid two-phase flow patterns in ultra-shallow straight and serpentine microchannels

Micro‐computed tomography for the 3D time‐resolved investigation of monodisperse droplet generation in a co‐flow setup

A comparison of different geometrical elements to model fluid wicking in paper‐based microfluidic devices

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