CFD analysis of microfluidic droplet formation in non–Newtonian liquid

Sontti, Somasekhara Goud; Atta, Arnab

doi:10.1016/j.cej.2017.07.097

Cited by 82 publications

(41 citation statements)

References 68 publications

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“…Additionally, a scaling relation is derived to determine the non‐dimensional bubble length as a function of modified capillary number ( Ca ′ = ( η 0 − η ∞ )λ n−1 U n D ( 1−n ) /σ) for the range of CMC concentration from 0.01–1.0 % (i.e., Ca ′ = 0.037 − 0.602) in Figure , where gas and liquid inlet velocities are kept constant at 0.5 m/s). The proposed scaling law relation L B = 1.23( Ca ′) −0.057 for different CMC solutions shows a maximum deviation of 1.2 %, and is in line with other non‐Newtonian studies, but with a different pre‐factor and exponent.…”

Section: Resultssupporting

confidence: 89%

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CFD study on Taylor bubble characteristics in Carreau‐Yasuda shear thinning liquids

Sontti

Atta

2018

Can J Chem Eng

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In the present study, Taylor bubble formation in two‐phase gas‐non‐Newtonian Carreau liquid flowing through a confined co‐flow microchannel is investigated. Systematic analyses are carried out to explore the influences of rheological properties, inlet velocities, and surface tension on Taylor bubble length, shape, velocity, and liquid film thickness. Aqueous solutions of carboxymethyl cellulose (CMC) with different mass concentrations are considered as the non‐Newtonian liquids to understand the fundamentals of flow behaviour. With increasing solution viscosity and liquid phase inlet velocity, Taylor bubble formation frequency and velocity increased; however, the bubble length was found to decrease. Velocity profiles inside the Taylor bubble and liquid slug were analyzed, and distinct velocity distributions were found for different CMC concentrations. Flow regime maps are developed based on gas and liquid velocities for Carreau liquids in the co‐flow microchannel. This study essentially provides useful guidelines in designing a non‐Newtonian microfluidic system for precise control and manipulation of Taylor bubbles.

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Section: Resultssupporting

confidence: 89%

“…[12] In our previous works, we also had implemented the VOF method for Taylor bubble formation in Newtonian and non-Newtonian systems. [34,40] Accordingly, in this work, the VOF method is further exercised for Carreau liquids, and the following set of governing equations are solved to identify the interface in the computational domain.…”

Section: Numerical Modelmentioning

confidence: 99%

CFD study on Taylor bubble characteristics in Carreau‐Yasuda shear thinning liquids

Sontti

Atta

2018

Can J Chem Eng

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“…16,17 As extensions of Newtonian uids, non-Newtonian uids are investigated numerically, for applications of polymers in fabricating complex delicate structures. 18,19 It is also found that the high inertial ow can bring some differences in droplet generation, for the case of water-in-air systems. 20 An enormous amount of research reveals that the viscosity ratio l and ow rate ratio Q of the dispersed phase to continuous phase, surface tension between the two phases, and contact angle have signicant inuences on droplet generation.…”

Section: Introductionmentioning

confidence: 94%

Effects of wall velocity slip on droplet generation in microfluidic T-junctions

Song

et al. 2019

RSC Adv.

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“…Other factors such as elasticity, wall-adhesion, viscoelasticity, and bending elasticity of the droplet were neglected. 2,[18][19][20] ANALYTICAL METHOD…”

Section: Physical Model and Assumptionsmentioning

confidence: 99%

Pressure of a viscous droplet squeezing through a short circular constriction: An analytical model

et al. 2018

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The model of a droplet squeezed through a narrow-constricted channel has many applications in pathology, chip/filter/membrane design, drug delivery, etc. Understanding the transient physics of the squeezing process is important in the design and optimization of many micro flow systems. However, available models often ignore the influence of droplet viscosity, and they usually feature low numerical efficiency by solving Navier-Stokes equations. In the present research, we developed a low-dimension analytical model to predict the pressure of squeezing a viscous droplet through a circular constricted channel with acceptable fidelity and low computational cost. Our approach is as follows. We first adapt the Hagen-Poiseuille law to predict the viscosity effect of droplet squeezing. Next, we obtain an analytical expression for the extra pressure caused by only the curvature change obtained. Finally, the general expression of squeezing pressure taking consideration of viscosity and surface tension is expressed. The analytical model we developed is in great agreement with the numerical solutions of the Navier-Stokes equation at a low Reynolds number and low capillary number. These findings have fundamental significance for future applications in engineering and industry.

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CFD analysis of microfluidic droplet formation in non–Newtonian liquid

Cited by 82 publications

References 68 publications

CFD study on Taylor bubble characteristics in Carreau‐Yasuda shear thinning liquids

CFD study on Taylor bubble characteristics in Carreau‐Yasuda shear thinning liquids

Effects of wall velocity slip on droplet generation in microfluidic T-junctions

Pressure of a viscous droplet squeezing through a short circular constriction: An analytical model

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