Dynamics of a Taylor bubble through a shear-thinning fluid up to finite capillary numbers

Aquino, Andrea; Picchi, Davide; Poesio, Pietro

doi:10.1016/j.jnnfm.2023.105003

Cited by 4 publications

(1 citation statement)

References 45 publications

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“…The case of an elongated bubble moving through a horizontal capillary has been widely investigated and is of relevance to microfluidics or lab-on-a-chip technology (Abbyad et al, 2011;Aquino et al, 2023;Arias and González-Cinca, 2016;Magnini et al, 2019Magnini et al, , 2022Murai et al, 2007;Perkins and Li, 2020). A circular cross-section of the capillary results in approximately cylindrical bubble shapes (Atasi et al, 2018;Zhao et al, 2018), with the formation of a thin liquid film separating the bubble from the capillary wall (Atasi et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Equilibrium shape of a bubble in a liquid-filled horizontal capillary

Jing,

Feng,

Ryan-Purcell

et al. 2024

International Journal of Multiphase Flow

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Section: Introductionmentioning

confidence: 99%

Equilibrium shape of a bubble in a liquid-filled horizontal capillary

Jing,

Feng,

Ryan-Purcell

et al. 2024

International Journal of Multiphase Flow

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Yield Stress Effects on the Dynamics and Liquid Film Thickness of a Taylor Bubble Rising in Vertical and Inclined Tubes

Li,

Duan,

Pang

et al. 2024

Ind. Eng. Chem. Res.

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In this work, the rising dynamics of a threedimensional (3D) Taylor bubble in vertical and inclined tubes filled with yield stress fluids are investigated by means of direct numerical simulations. The gas−liquid interface is captured by the volume-of-fluid (VOF) method with adaptive mesh refinement technique. The Herschel−Bulkley model is used to evaluate the rheological behavior of viscoplastic fluids that exhibit a yield response. The reliability of the present simulation to capture the bubble shape and liquid film for a deformed Taylor bubble is validated by comparisons with experimental results in the literature. Our findings reveal a non-monotonic correlation between the stable bubble velocity and yield stress values across a broad range of values. The interplay among the shear stress generated by the rising bubble, the fluid's yield stress, and the pressure gradient due to changes in the liquid film thickness is primarily responsible for this phenomenon. In addition, different from the symmetrical liquid film and flow field observed in vertical tubes, the symmetrical characteristic is lost in inclined tubes. The results also reproduce the peculiar phenomenon that the rise velocity of Taylor bubbles peaks at a certain inclination angle in yield stress fluids. At smaller inclined angles, the shear stress generated by the tail flow field could overcome yield stress, causing the fluid around the bubble tail to have shear-thinning characteristics. As the tube further tilts, the lower liquid film gradually thickens, and the bubbles behave as if they are in a Newtonian fluid. This work provides important insights into the petroleum industry involving complex yield stress fluids, as well as an understanding of the mechanisms of Taylor bubble dynamics in inclined tubes.

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Draining of shear-thinning liquids from closed-top millichannels

Samanta,

Priyanka,

Roy

et al. 2023

Physics of Fluids

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Draining from a closed-top tube occurs by downward displacement of liquid by air. The air volume grows inside the tube as an axisymmetric bullet-shaped finger similar to the Taylor bubble observed in gas–liquid slug flows, and the liquid drains as an annular film between the finger and the tube wall. The present study investigates the draining of shear-thinning vis-à-vis Newtonian liquids from closed-top circular millichannels. Numerical simulations using the phase-field method suggest that both the power law and Carreau models give close predictions of draining behavior in the investigated domain, i.e., for shear rate >0.1 s−1. The results are validated against experimental measurements based on high-speed photography and particle image velocimetry during the draining of aqueous solutions of carboxymethyl cellulose, xanthan gum, and glycerol. Further validations are performed for shear-thinning (using the power law, Carreau, and Carreau–Yasuda models) and Newtonian liquids with literature data on Taylor bubble rise in stationary liquid columns. The simulations using the power law model are used to explore additional insights into the flow physics. An increase in the apparent viscosity of shear-thinning liquids (by increasing the flow behavior index and/or flow consistency index) slows down the rate of Taylor finger growth. Increased liquid viscosity also results in a slender Taylor finger and leaves a higher amount of undrained liquid at the end of film-wise draining. The draining rate is a more significant function of flow behavior index n of the power law model for highly shear-thinning liquids (n < 0.6).

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Dynamics of a Taylor bubble through a shear-thinning fluid up to finite capillary numbers

Cited by 4 publications

References 45 publications

Equilibrium shape of a bubble in a liquid-filled horizontal capillary

Equilibrium shape of a bubble in a liquid-filled horizontal capillary

Yield Stress Effects on the Dynamics and Liquid Film Thickness of a Taylor Bubble Rising in Vertical and Inclined Tubes

Draining of shear-thinning liquids from closed-top millichannels

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