Flow patterns in liquid slugs during bubble-train flow inside capillaries

Thulasidas, T.C.; Abraham, Martín; Cerro, Ramón L.

doi:10.1016/s0009-2509(97)00114-0

Cited by 308 publications

(209 citation statements)

References 14 publications

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“…5(b-d), the secondary flow caused by the curvature was also observed. The maximum primary liquid velocity around the center of the cross-section far from the bubbles is about 1.8 times higher 31,32 than the bubble velocity with a capillary number of 2.7 × 10 −4 . Therefore, a toroidal vortex per liquid slug was generated before and after the bubbles and made a longitudinal recirculation flow when this flow was seen in a coordinate system moving with the bubbles.…”

Section: Resultsmentioning

confidence: 87%

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Optical sectioning for microfluidics: secondary flow and mixing in a meandering microchannel

2008

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Secondary flow plays a critical function in a microchannel, such as a micromixer, because it can enhance heat and mass transfer. However, there is no experimental method to visualize the secondary flow and the associated mixing pattern in a microchannel because of difficulties in high-resolution, non-invasive, cross-sectional imaging. Here, we simultaneously imaged and quantified the secondary flow and pattern of two-liquid mixing inside a meandering square microchannel with spectral-domain Doppler optical coherence tomography. We observed an increase in the efficiency of two-liquid mixing when air was injected to produce a bubble-train flow and identified the three-dimensional enhancement mechanism behind the complex mixing phenomena. An alternating pair of counterrotating and toroidal vortices cooperated to enhance two-liquid mixing.

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Section: Resultsmentioning

confidence: 87%

“…The hypothesis was that injecting air into two liquids enhances mixing. By injecting air, a bubble-train flow [30][31][32] was sustained in a quasi-steady-state. Through the third experiment, the velocity field, which governs a mixing phenomenon, was imaged.…”

Section: Resultsmentioning

confidence: 99%

Optical sectioning for microfluidics: secondary flow and mixing in a meandering microchannel

2008

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“…Low axial mass transfer or back mixing occurs between two adjacent liquid slugs. Moreover, both radial mass and heat transfer can be intensified by internal circulation in the single slugs (Günther et al, 2004;Thulasidas et al, 1997). These merits make slug flow an ideal regime for improving the reaction performance.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of slug flow with inertial effects in a rectangular microchannel

Yao

Zhao

et al. 2013

Chemical Engineering Science

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“…Owing to the assumption that a flow is symmetric around the pipe centerline, the computation domain is just half a unit of the slug flow as shown in Fig.2a Taylor bubbles were usually observed in pipes, ranging from very-small-size pipes as capillary tubes [14][15]24] to middle-size pipes ( p D < 0.1 m) [25][26]. This was because, in a 10 cm pipe, bubbly flows underwent a regime transition to churn-turbulence (not to slug flows as typically observed in smaller diameter pipes) [27].…”

Section: Computational Setupmentioning

confidence: 99%

Shapes of an Air Taylor Bubble in Stagnant Liquids Influenced by Different Surface Tensions

Lertnuwat

2018

International Journal of Applied Mechanics and Engineering

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The aim of this work is to propose an empirical model for predicting shapes of a Taylor bubble, which is a part of slug flows, under different values of the surface tension in stagnant liquids by employing numerical simulations. The k   turbulence model was used in the framework of finite volume method for simulating flow fields in a unit of slug flow and also the pressure distribution on a Taylor bubble surface. Assuming that an air pressure distribution inside the Taylor bubble must be uniform, a grid search method was exploited to find an appropriate shape of a Taylor bubble for six values of surface tension. It was found that the shape of a Taylor bubble would be blunter if the surface tension was increased. This was because the surface tension affected the Froude number, controlling the flow around a Taylor bubble. The simulation results were also compared with the Taylor bubble shape, created by the Dumitrescu-and-Taylor model and former studies in order to ensure that they were consistent. Finally, the empirical model was presented from the simulation results.

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Flow patterns in liquid slugs during bubble-train flow inside capillaries

Cited by 308 publications

References 14 publications

Optical sectioning for microfluidics: secondary flow and mixing in a meandering microchannel

Optical sectioning for microfluidics: secondary flow and mixing in a meandering microchannel

Characteristics of slug flow with inertial effects in a rectangular microchannel

Shapes of an Air Taylor Bubble in Stagnant Liquids Influenced by Different Surface Tensions

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