Film drainage mechanism between two immiscible droplets

Choi, Se Bin; Lee, Joon Sang

doi:10.1007/s10404-014-1379-x

Cited by 16 publications

(13 citation statements)

References 23 publications

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“…The viscous shearing stress of the moving surface carries the surrounding fluid into the liquid film between the contacting microdroplets, making it difficult to drain out the liquid film. Currently, most studies on the theory of liquid film drainage focus on head-on contact of round microdroplets (Wang et al 2013a, Yang et al 2012; Choi and Lee 2014; Liao and Lucas 2010); rotation of microdroplets has attracted research attention only in a few studies (Wang et al 2013a). …”

Section: Resultsmentioning

confidence: 99%

“…Most of previous studies mainly focused on the droplet interface deformation and interfacial tension using microscope observations. However, relatively few studies have focused on droplet behaviors during merging and splitting in microchannels, in which droplets controlled by the surrounding viscous liquid, can deform significantly on accounting of the confining boundaries (Christopher et al 2009; Choi and Lee 2014; Gu et al 2011), leading to series of new fluid dynamics problems such as the change of the interfacial tension and nonlinear problems of droplets (Baroud et al 2010; Raven and Marmottant 2006; Guillot et al 2008; Chen et al 2011). …”

Section: Introductionmentioning

confidence: 99%

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Study of flow behaviors of droplet merging and splitting in microchannels using Micro-PIV measurement

Shen

Liu

et al. 2017

Microfluid Nanofluid

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Droplet merging and splitting are important droplet manipulations in droplet-based microfluidics. However, the fundamental flow behaviors of droplets were not systematically studied. Hence, we designed two different microstructures to achieve droplet merging and splitting respectively, and quantitatively compared different flow dynamics in different microstructures for droplet merging and splitting via micro-particle image velocimetry (micro-PIV) experiments. Some flow phenomena of droplets different from previous studies were observed during merging and splitting using a high-speed microscope. It was also found the obtained instantaneous velocity vector fields of droplets have significant influence on the droplets merging and splitting. For droplet merging, the probability of droplets coalescence (η) in a microgroove is higher (50% < η < 92%) than that in a T-junction microchannel (15% < η < 50%), and the highest coalescence efficiency (η = 92%) comes at the two-phase flow ratio e of 0.42 in the microgroove. Moreover, compared with a cylinder obstacle, Y-junction bifurcation can split droplets more effectively and the droplet flow during splitting is steadier. The results can provide better understanding of droplet behaviors and are useful for the design and applications of droplet-based microfluidics.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of flow behaviors of droplet merging and splitting in microchannels using Micro-PIV measurement

Shen

Liu

et al. 2017

Microfluid Nanofluid

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“…The drainage of the interfacial thin film is a complex part of the coalescence mechanism, which was studied by several researchers. [23,24] The detail of film drainage theory is beyond the scope of this research and only briefly described here.…”

Section: Droplet Coalescencementioning

confidence: 99%

Evaluation of adsorption of nonionic surfactants blend at water/oil interfaces

Nourafkan

2017

Journal of Dispersion Science and Technology

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The inherent biocompatibility of Span and Tween surfactants make them as an important class of nonionic emulsifiers which are employed extensively in emulsion and foam stabilization. The adsorption of Span-Tween blend at water/oil surface of emulsion has been investigated using a population balance model for the first time. Destability of emulsion was modeled by considering sedimentation, coalescence and interfacial coalescence terms in population balance equation (PBE). The terms of coalescence efficiency and interfacial coalescence time were considered as a function of surface coverage of droplets by surfactant molecules. The surface coverage at different surfactant concentrations was determined by minimization of difference between the model predictions and experimental average droplet sizes. After optimization, the surface coverage outputs were fitted with different adsorption isotherms to evaluate the adsorption behavior of Span-Tween surfactants blend at water/oil surface. The results show that Freundlich isotherm can predict the adsorption behavior of closer to the experimental observation. Moreover, fitted parameters imply the favorable adsorption of Span-Tween blend at water/oil interface.

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“…[3][4][5][6][7][8][9][10] The effects of surface-active agents on droplet deformation in a linear extensional flow at low Reynolds numbers were analyzed. The analytical and numerical results indicated that at low capillary numbers, the presence of surfactant caused larger deformation than would occur for a droplet with a constant interfacial tension.…”

Section: Introductionmentioning

confidence: 99%

“…9 The film drainage of two immiscible droplets exhibited additional flow into or out of the film and this additional flow could either increase or decrease the rate of film drainage between the droplets, depending on the interfacial tension of droplets with the surrounding fluid and the interfacial tension of the two immiscible droplets. 10 Many researchers have used molecular dynamics (MD) to investigate interfacial properties at the atomic-scale. MD simulation can provide clear insight into the structural characteristics of the interface.…”

Section: Introductionmentioning

confidence: 99%

Multi-scale approach for the rheological characteristics of emulsions using molecular dynamics and lattice Boltzmann method

2014

Self Cite

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An emulsion system was simulated under simple shear rates to analyze its rheological characteristics using a hierarchical multi-scale approach. The molecular dynamics (MD) simulation was used to describe the interface of droplets in an emulsion. The equations derived from the MD simulation relative to interfacial tension, temperature, and surfactant concentration were applied as input parameters within lattice Boltzmann method (LBM) calculations. In the LBM simulation, we calculated the relative viscosity of an emulsion under a simple shear rate along with changes in temperature, shear rate, and surfactant concentration. The equations from the MD simulation showed that the interfacial tension of the droplets tended to decrease with an increase in temperature and surfactant concentration. The relative viscosity from the LBM simulation decreased with an increase in temperature. The shear thinning phenomena explaining the inverse proportion between shear rate and viscosity were observed. An increase in the surfactant concentration caused an increase in the relative viscosity for a decane-in-water emulsion, because the increased deformation caused by the decreased interfacial tension significantly influenced the wall shear stress. V C 2014 AIP Publishing LLC.

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Film drainage mechanism between two immiscible droplets

Cited by 16 publications

References 23 publications

Study of flow behaviors of droplet merging and splitting in microchannels using Micro-PIV measurement

Study of flow behaviors of droplet merging and splitting in microchannels using Micro-PIV measurement

Evaluation of adsorption of nonionic surfactants blend at water/oil interfaces

Multi-scale approach for the rheological characteristics of emulsions using molecular dynamics and lattice Boltzmann method

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