The Mechanisms of Bubble Coalescence in a Non‐Newtonian Fluid

Lin, Tsao-Jen; Lin, Gen-Ming

doi:10.1002/cjce.5450810320

Cited by 16 publications

(7 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…6 The flow field during in-line bubble coalescence revealed that the dragging force and pushing force generated by shear-thinning effect and viscoelastic effect respectively play important role in the course of bubble coalescence in non-Newtonian fluid. 7 Recently, more and more researchers 8−12 make use of various numerical methods such as Volume of Fluid method (VOF), Level Set method (LS), Lattice Boltzmann method (LB), and Front Tracking method (FT) to investigate bubble dynamics or interactions, in general, their studied results were in reasonable agreement with the existing experimental data. However, it should be pointed out that bubble coalescence occurs numerically as soon as the interfaces come closer than the grid width for numerical technique of VOF, LS, and LB.…”

Section: Introductionmentioning

confidence: 79%

Systematic Study on the Coalescence and Breakup Behaviors of Multiple Parallel Bubbles Rising in Power-law Fluid

Liu

Zhu

2014

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

The coalescence and breakup behaviors of multiple parallel bubbles rising in power-law non-Newtonian fluid were investigated numerically by Volume of Fluid (VOF) method. The effects of the number of bubbles, bubble diameter, bubble interval, and flow index of power-law fluid on bubble coalescence and breakup were studied systematically. The dimensionless critical horizontal intervals of bubble coalescence for two, three, and four bubbles with different diameters were attained respectively by simulation under different flow indexes of power-law fluid. A quantitative criterion was developed to compute the critical bubble interval for bubble coalescence based on the critical approach velocity theory. Dramatic deformations of bubbles were found during the coalescence processes. Two different bubble coalescence and breakup behaviors were found and illustrated: (I) all bubbles coalesce into one big bubble; (II) coalescence of partial bubbles among multiple bubbles. For two or three parallel bubbles, only regime (I) occurs. However, for four parallel bubbles, other than the coalescence into one big bubble and subsequent breakup, the collision and coalescence between two neighboring bubbles among the four parallel bubbles could take place more easily. The breakup of the coalescing bubble usually appears in the cases of big bubble size and low flow index of power-law fluid.

show abstract

Section: Introductionmentioning

confidence: 79%

Systematic Study on the Coalescence and Breakup Behaviors of Multiple Parallel Bubbles Rising in Power-law Fluid

Liu

Zhu

2014

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

show abstract

“…In shear-thinning fluids, the local perturbation due to a rising bubble-or a falling sphere-creates a negative wake [23] and a corridor of reduced viscosity [24,25]. As a consequence, successive bubbles may interact one with one another [26][27][28][29], if the emission period is shorter than the time for the perturbation created by the bubble to vanish.…”

Section: Introductionmentioning

confidence: 99%

Degassing cascades in a shear-thinning viscoelastic fluid

et al. 2011

View full text Add to dashboard Cite

We report the experimental study of the degassing dynamics through a thin layer of shear-thinning viscoelastic fluid when a constant air flow is imposed at its bottom. The fluid is an aqueous solution of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal). Over a large range of parameters, the air is periodically released through a series of successive bubbles, hereafter named cascades. Each cascade is followed by a continuous degassing, lasting for several seconds, corresponding to an open channel crossing the fluid layer. The periodicity between two cascades does not depend on the injected flow rate. Inside one cascade, the properties of the overpressure signal associated with the successive bubbles vary continuously. The pressure threshold above which the fluid starts flowing, fluid deformation and pressure drop due to degassing through the thin fluid layer can be simply described by a Maxwell model.

show abstract

“…A number of experimental studies have been reported on co‐axial bubbles (or a pair of bubbles rising in a vertical line) and their coalescence . For example, Katz and Meneveau experimentally investigated the rising motion of air bubbles in stagnant water at Reynolds number, Re = V ρ d o / μ , ranging from 0.2 to 35 and found that the collision between bubbles resulted mainly from wake‐induced relative motion.…”

Section: Introductionmentioning

confidence: 99%

“…They found that the bubbles collided at a low Reynolds number but not at an intermediate Reynolds number which had an equilibrium distance between the bubbles. Lin et al investigated co‐axial bubble coalescence mechanism in a non‐Newtonian fluid experimentally and found that shear‐thinning effect and viscoelastic effect play a vital role in the course of bubble coalescence.…”

Section: Introductionmentioning

confidence: 99%

Coalescence and rising behavior of co‐axial and lateral bubbles in viscous fluid: a CFD study

Ganesan

Islam

Pokrajac

et al. 2017

Asia-Pacific J Chem Eng

View full text Add to dashboard Cite

The coalescence and rising behavior of co-axial and lateral bubbles play a valuable role in industrial bubble column which operates at non-ambient conditions. The volume of fluid with the continuum surface force (VOF-CSF) model is used for the present study. Three main case studies, namely under ambient and aqueous condition, μ* = σ* = 1, under reduced viscosity, μ* = 0.1, and surface tension, σ* = 0.1, are investigated and compared using two co-axial bubbles and three lateral bubble rise configuration models. The latter two cases represent operating conditions at above the ambient temperature or pressure. Prior to investigating the main cases, the model is validated with the experimental data from the literature for a single bubble and two lateral bubble coalescence. It is found that reducing viscosity and surface tension has a significant effect on the co-axial bubbles (or a pair of bubbles rising in a vertical line) and three lateral bubble growth and coalescence characteristics, as compared to ambient condition.Noted: μ r and σ r represent the reduced liquid viscosity and surface tension, respectively. P. B. GANESAN ET AL. Asia-Pacific Journal of Chemical Engineering 608 S c = 0.136 or Δx c = 0.816 mm; t = 0.046 s; (c) S c = 0.11 or Δx c = 0.88 mm, t = 0.039 s. Please refer to inset arrows for graphical clarity.Figure 11. (a-f) Effect of initial lateral gap, S, for different diameters of bubble, d b . P. B. GANESAN ET AL. Asia-Pacific Journal of Chemical Engineering 614

show abstract

The Mechanisms of Bubble Coalescence in a Non‐Newtonian Fluid

Cited by 16 publications

References 12 publications

Systematic Study on the Coalescence and Breakup Behaviors of Multiple Parallel Bubbles Rising in Power-law Fluid

Systematic Study on the Coalescence and Breakup Behaviors of Multiple Parallel Bubbles Rising in Power-law Fluid

Degassing cascades in a shear-thinning viscoelastic fluid

Coalescence and rising behavior of co‐axial and lateral bubbles in viscous fluid: a CFD study

Contact Info

Product

Resources

About