Prediction of film thickness, bubble velocity, and pressure drop for capillary slug flow using a CFD-generated database

Langewisch, Dustin R.; Buongiorno, Jacopo

doi:10.1016/j.ijheatfluidflow.2015.06.005

Cited by 31 publications

(13 citation statements)

References 35 publications

(46 reference statements)

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“…In this case, Eqs. (35) and (36) reduce to the well known predictions for bubbles (2 − H ∞ /R)H ∞ /R and H ∞ /R [9,54,39], respectively (see Fig. 16(a)).…”

Section: Droplet Velocitysupporting

confidence: 54%

Viscous Taylor droplets in axisymmetric and planar tubes: from Bretherton’s theory to empirical models

Balestra

Zhu

Gallaire

2018

Microfluid Nanofluid

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The aim of this study is to derive accurate models for quantities characterizing the dynamics of droplets of non-vanishing viscosity in capillaries. In particular, we propose models for the uniform-film thickness separating the droplet from the tube walls, for the droplet front and rear curvatures and pressure jumps, and for the droplet velocity in a range of capillary numbers, Ca, from 10 −4 to 1 and inner-to-outer viscosity ratios, λ , from 0, i.e. a bubble, to high viscosity droplets. Theoretical asymptotic results obtained in the limit of small capillary number are combined with accurate numerical simulations at larger Ca. With these models at hand, we can compute the pressure drop induced by the droplet. The film thickness at low capillary numbers (Ca < 10 −3 ) agrees well with Bretherton's scaling for bubbles as long as λ < 1. For larger viscosity ratios, the film thickness increases monotonically, before saturating for λ > 10 3 to a value 2 2/3 times larger than the film thickness of a bubble. At larger capillary numbers, the film thickness follows the rational function proposed by Aussillous & Quéré [5] for bubbles, with a fitting coefficient which

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“…In this case, Eqs. (35) and (36) reduce to the well known predictions for bubbles (2 − H ∞ /R)H ∞ /R and H ∞ /R [9,54,39], respectively (see Fig. 16(a)).…”

Section: Droplet Velocitysupporting

confidence: 54%

Viscous Taylor droplets in axisymmetric and planar tubes: from Bretherton’s theory to empirical models

Balestra

Zhu

Gallaire

2018

Microfluid Nanofluid

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“…Ever since, the dynamics of the elongated bubble, in particular of its front meniscus, have been investigated extensively, e.g. effects of inertia [3][4][5][6][7], profiles of the bubble [6,8,9], streamlines ahead of the bubble tip [4,10] and pressure drop [4,8,11,12]. A summary of the studies that are relevant to the present work (Re 1) is provided in Table I.…”

Section: Introductionmentioning

confidence: 99%

Undulations on the surface of elongated bubbles in confined gas-liquid flows

et al. 2017

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A systematic analysis is presented of the undulations appearing on the surface of long bubbles in confined gas-liquid flows. CFD simulations of the flow are performed with a self-improved version of the open-source solver ESI OpenFOAM (release 2.3.1), for Ca = 0.002−0.1 and Re = 0.1−1000, where Ca = µU/σ and Re = 2ρU R/µ, with µ and ρ being, respectively, the viscosity and density of the liquid, σ the surface tension, U the bubble velocity and R the tube radius. A model, based on an extension of the classical axisymmetric Bretherton theory, accounting for inertia and for the curvature of the tube's wall, is adopted to better understand the CFD results. The thickness of the liquid film, and the wavelength and decay rate of the undulations extracted from the CFD simulations, agree well with those obtained with the theoretical model. Inertial effects appear when the Weber number of the flow We = Ca Re = O(10 −1 ) and are manifest by a larger number of undulation crests that become evident on the surface of the rear meniscus of the bubble. This study demonstrates that the necessary bubble length for a flat liquid film region to exist between the rear and front menisci rapidly increases above 10R when Ca > 0.01 and the value of the Reynolds number approaches 1000.

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“…Simple empirical correlations have been proposed to estimate h 0 as a function of Ca and Re, see e.g. Aussillous and Quéré [16], Han and Shikazono [19] and Langewisch and Buongiorno [20], and these have been utilized to interpret experimental observations about colloid detachment performances [3,14,12]. However, the liquid film thickness around elongated bubbles is not constant, as undulations may appear near the bubble tail and make the liquid film significantly thinner than h 0 [21,22,23,24], which is the thickness measured at a location which is sufficiently distant from the front and rear menisci of the bubble, where the liquid film is flat.…”

Section: Introductionmentioning

confidence: 99%

Pore-scale analysis of the minimum liquid film thickness around elongated bubbles in confined gas-liquid flows

Magnini

Beisel

Ferrari

et al. 2017

Advances in Water Resources

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Prediction of film thickness, bubble velocity, and pressure drop for capillary slug flow using a CFD-generated database

Cited by 31 publications

References 35 publications

Viscous Taylor droplets in axisymmetric and planar tubes: from Bretherton’s theory to empirical models

Viscous Taylor droplets in axisymmetric and planar tubes: from Bretherton’s theory to empirical models

Undulations on the surface of elongated bubbles in confined gas-liquid flows

Pore-scale analysis of the minimum liquid film thickness around elongated bubbles in confined gas-liquid flows

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