Transient analysis of a single rising bubble used for numerical validation for multiphase flow

Keshavarzi, Gholamreza; Pawell, Ryan S.; Barber, Tracie; Yeoh, Guan Heng

doi:10.1016/j.ces.2014.02.027

Cited by 28 publications

(11 citation statements)

References 27 publications

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“…One of the key steps in such methodologies is the surface tension modeling, and improper model implementation in balance between capillary force and pressure jump across the interface can lead to the evolution of unphysical velocities near the interface, known as spurious currents . , Several researchers have attempted to reduce spurious currents with different approaches. − Sussman and Puckett developed a coupled LS and VOF (CLSVOF) technique that smoothly captured the continuous interface by calculating the radius of curvature from the LS function. This method has later been successfully utilized to unravel the physics in various applications, e.g., bubble rise in viscous liquids, bubble formation on submerged orifices, droplet impact on a liquid pool, Taylor bubble formation, − axisymmetric droplet formation, droplet coalescence, and demulsification . In this work, we present a comprehensive numerical study based on the CLSVOF method, which is arguably better in interface tracking for low Capillary number systems than the conventional VOF technique to delineate the droplet formation mechanism and flow patterns in a microfluidic flow-focusing device.…”

Section: Introductionmentioning

confidence: 99%

Numerical Insights on Controlled Droplet Formation in a Microfluidic Flow-Focusing Device

Sontti

Atta

2019

Ind. Eng. Chem. Res.

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In this article, we have developed a computational model to determine the droplet formation regime and its transition in a square microfluidic flow-focusing device that eventually dictate the droplet shape, size, and its formation frequency. We have methodically explored the influences of various physicochemical parameters on the droplet dynamics and flow regime transition, which are essential in the development of new methods for on-demand droplet generation. On the basis of the droplet formation mechanism, we have formulated flow maps for different liquid−liquid systems, and have also proposed a scaling law to predict the droplet length for a wide range of operating condition resulting from the variation of flow rates, and viscosities of the continuous phase as well as the interfacial tension. This work can effectively contribute in providing helpful guidelines on the design and operations of droplet-based flow-focusing microfluidic systems.

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Section: Introductionmentioning

confidence: 99%

Numerical Insights on Controlled Droplet Formation in a Microfluidic Flow-Focusing Device

Sontti

Atta

2019

Ind. Eng. Chem. Res.

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“…In contrast, for the nozzle with the outlet diameter of 1.0 mm, the bubble rising trajectory retains a roughly rectilinear pattern. The trend that small bubbles are associated with relatively straight trajectories has been reported in 24 . Moreover, such a trend is tenable as bubbles rise in n ‐pentanol solutions, which has been demonstrated in the work of Krzan et al 25 …”

Section: Resultsmentioning

confidence: 93%

Quantitative characterization of bubble evolution in mineral oil for different air‐injection nozzles

Mao

Kang

Teng

et al. 2020

Asia-Pacific J Chem Eng

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The aim of the present study is to reveal characteristics of a rising bubble in quiescent mineral oil. Three air-injection nozzles with outlet diameters of 1.0, 2.0, and 3.0 mm were selected. Consecutively rising bubbles were produced as air was injected into mineral oil. Bubble visualization was implemented using the high-speed photography technique. Bubble images captured were processed using an in-house code to calculate the equivalent bubble diameter and the bubble velocity. The computational fluid dynamics technique was used to simulate flows around the rising bubble. The bubble trajectory, the bubble aspect ratio, and the bubble velocity were compared among the three nozzles. Correlations between nondimensional parameters were constructed. The results show that the bubble motion in mineral oil is stabilized in comparison with that in deionized water. Spherical and ellipsoidal shapes are prevalent.The bubble trajectory is rectilinear, which is independent of the nozzle outlet diameter. After the bubble separates from the nozzle, the equilibrium state is promptly attained. Smooth bubble evolution is ascribed to suppressed wake vortices immediately downstream of the bubble. Small nozzle outlet diameter is responsible for high aspect ratio but small Eötvös number. Values of the Weber number are much smaller than those associated with deionized water.The drag coefficient descends continuously with increasing Reynolds number (Re); the correspondence between the drag coefficient and Re is explicitly sensitive to the nozzle outlet diameter. K E Y W O R D Sbubble, bubble aspect ratio, bubble trajectory, drag coefficient, mineral oil, visualization

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“…Studies of bubble motion in confined situations were reported by Krishna et al (1999), FigueroaEspinoza et al (2008), Roig et al (2012), Böhm et al (2014), Keshavarzi et al (2014) and Tripathi et al (2015b). Krishna et al (1999) explored the effects of the wall on the rise velocity of a single gas bubble rising in a vertical liquid column.…”

Section: Introductionmentioning

confidence: 94%

“…The terminal Reynolds number varied as Ar/2 for a wide range of Ar. Keshavarzi et al (2014) considered bubble rise in a thin rectangular channel and their computations assumed two-dimensionality. Böhm et al (2014) investigated the effects of channel depth, bubble size, superimposed liquid velocity and fluid rheology on the motion of a single bubble in a narrow rectangular channel.…”

Section: Introductionmentioning

confidence: 99%

Effects of confinement on bubble dynamics in a square duct

Vanka

2015

International Journal of Multiphase Flow

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In this paper, we simulate the effects of confinement on three-dimensional bubble dynamics in a square duct. A systematic study of three confinement ratios, four Bond numbers and two Morton numbers has been conducted. A GPU implemented VOF numerical algorithm on a Cartesian collocated grid with an improved method to handle the surface tension force has been developed. A three-dimensional geometry construction method with a piecewise linear interpolation scheme for approximating the interface segments is used to compute the interface shape and liquid volume flux from the cell faces. The Navier-Stokes equations are solved with a space-time second-order accurate fractional step numerical scheme. The surface tension force is treated as a pressure gradient and an additional Poisson equation is solved. Transient and steady state bubble deformations, rise velocities and aspect ratios are presented.

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Transient analysis of a single rising bubble used for numerical validation for multiphase flow

Cited by 28 publications

References 27 publications

Numerical Insights on Controlled Droplet Formation in a Microfluidic Flow-Focusing Device

Numerical Insights on Controlled Droplet Formation in a Microfluidic Flow-Focusing Device

Quantitative characterization of bubble evolution in mineral oil for different air‐injection nozzles

Effects of confinement on bubble dynamics in a square duct

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