Bubble-wall interactions in a vertical gas–liquid flow: Bouncing, sliding and bubble deformations

Zaruba, A.; Lucas, Dirk; Prasser, Horst-Michael; Höhne, Thomas

doi:10.1016/j.ces.2006.11.044

Cited by 45 publications

(23 citation statements)

References 23 publications

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“…The typical wobbling shape of the bubble (see figures 1b and 3) in the present set-up is in a good agreement with the classification of the bubble shape depending on Re and Eo, proposed by Clift et al (1978). Note that the present wobbling bubble shape is approximated as an oblate ellipsoid and its geometric variables are calculated accordingly, as done by many previous studies (Zaruba et al 2007;Zenit & Magnaudet 2008;Cano-Lozano, Bohorquez & Martínez-Bazán 2013). On the other hand, for the present d eq and Re, it is known that a freely rising bubble follows an in-plane zigzag oscillation (Clift et al 1978;Ellingsen & Risso 2001;Zenit & Magnaudet 2008), which we also confirmed (figure 1b).…”

Section: Experimental Set-up and Proceduressupporting

confidence: 82%

“…Previously, de Vries (2001) and Zaruba et al (2007) observed that a spherical rising bubble (d eq < 1 mm), smaller than the current one, also slides on the wall after a few bounces with gradually decreasing amplitudes. They attributed the cause of a transition from bouncing to sliding to the weakened inertia compared to the surface tension (de Vries 2001) or the balance between the wall-normal lift and drag forces (Zaruba et al 2007). Although the present bubble is much larger (∼3.9 mm) and bouncing amplitude tends to be maintained approximately constant (i.e.…”

Section: Sliding Bubblesmentioning

confidence: 97%

“…Moctezuma, Lima-Ochoterena & Zenit (2005) modelled the bouncing motion of a spherical bubble near a vertical wall in still water using the potential flow theory, representing the case of high Re and low We, and pointed out the importance of effects of viscosity in predicting the bubble's bouncing behaviour accurately. Zaruba et al (2007) constructed the equation of motion for a rising bubble (Re = 220-1000) near a vertical wall, under an upward shear, by considering associated force components 566 H. Jeong and H. Park acting on the bubble. They predicted the changes in the bubble's bouncing motion with varying liquid velocity, and hypothesized that at a low liquid velocity, the bubble obtains additional energy from the shape oscillation to compensate the damping effect during bubble-wall collisions and maintains the bouncing amplitude almost constant.…”

Section: Introductionmentioning

confidence: 99%

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Near-wall rising behaviour of a deformable bubble at high Reynolds number

Jeong

Park

2015

J. Fluid Mech.

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The dynamics of a large deformable bubble (Re ∼ O(10 3 )) rising near a vertical wall in quiescent water is experimentally investigated. The reference (without the wall) rising path of the considered bubble is a two-dimensional zigzag. For a range of wall configurations (i.e. initial wall distance and boundary condition), using high-speed shadowgraphy, various rising behaviours such as periodic bouncing, sliding, migrating away, and non-periodic oscillation without collisions are measured and analysed. Unlike low-Reynolds-and Weber-number bubbles, the contribution of the surface deformation to the transport between the energy components becomes significant during the bubble's rise. In particular, across the bubble-wall collision, the excess surface energy compensates the deficit of kinetic energy. This enables a large deformable bubble to maintain a relatively constant bouncing kinematics, despite the obvious wall-induced energy dissipation. The wall effect, predominantly appearing as energy loss, is found to decrease as the initial distance from the bubble centre to the wall increases. Compared to the regular (no-slip) wall, a hydrophobic surface enhances or reduces the wall effect depending on the wall distance, whereas a porous surface reduces the energy loss due to the wall, regardless of the initial distance from the wall. Furthermore, the bubble-wall collision behaviour is assessed in terms of a restitution coefficient and modified impact Stokes number (ratio of the inertia to viscous forces), which shows a good correlation, the trends of which agree well with the variations in the energy components. The dependence of near-wall bubble motion on the wall distance and boundary condition may suggest a way of predicting or controlling the near-wall gas void-fraction distribution in gas-liquid flow systems.

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Section: Experimental Set-up and Proceduressupporting

confidence: 82%

Section: Sliding Bubblesmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Near-wall rising behaviour of a deformable bubble at high Reynolds number

Jeong

Park

2015

J. Fluid Mech.

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“…In the case of air-water flow, the efficiency of the gas-lift technique can be improved by 20% when using small bubbles, which was reported in Guet (2004). Zaruba et al (2007) reported two types of motion for isolated bubbles in the vicinity of a wall, in a gas-liquid channel flow: a bouncing and a sliding motion. The bouncing motion for a single bubble could be theoretically predicted considering the drag, lift and deformation forces.…”

Section: Pressure Measurementsmentioning

confidence: 99%

Air–water flow in a vertical pipe: experimental study of air bubbles in the vicinity of the wall

et al. 2008

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This study deals with the influence of bubbles on a vertical air-water pipe flow, for gas-lift applications. The effect of changing the bubble size is of particular interest as it has been shown to affect the pressure drop over the pipe. Local measurements on the bubbles characteristics in the wall region were performed, using standard techniques, such as high-speed video recording and optical fibre probe, and more specific techniques, such as two-phase hot film anemometry for the wall shear stress and conductivity measurement for the thickness of the liquid film at the wall. The injection of macroscopic air bubbles in a pipe flow was shown to increase the wall shear stress. Bubbles travelling close to the wall create a periodic perturbation. The injection of small bubbles amplifies this effect, because they tend to move in the wall region; hence, more bubbles are travelling close to the wall. A simple analysis based on a two-fluid set of equations emphasised the importance of the local gas fraction fluctuations on the wall shear stress.

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“…According to Zaruba et al (2007), it is needed to consider a bubble deformation force that makes the bubble bounce when shocking with the pipe wall to prevent the bubble centre of mass displacement to be unrealistically close to the wall. Some researchers do not use this force depending on the effect of the wall lubrication force and consider that it is included in the wall lubrication force.…”

Section: Bubble Deformation Forcementioning

confidence: 99%

Coupled Lagrange-Euler Model for Simulation of Bubbly Flow in Vertical Pipes Considering Turbulent 3d Random Walks Models and Bubbles Interaction Effects

Essa¹

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A novel Two-way coupled Euler-Lagrange mode, including bubble-bubble collision, coalescence, with variable bubble radius, and bubbles breakup was applied to simulate air-water bubbly flow in vertical pipes. This approach uses the Continuous Random Walks CRW models for creating the velocity fluctuations according to the given state of turbulent kinetic energy and Dissipation rate at the location of the bubbles which is solved by the turbulence model. This dissertation i) describes the development of the Euler-Lagrange Approach under study, ii) presents a study for the two-way coupling effect on both the continuous and dispersed phases properties, iii) studies the effect of both the lift force coefficient and bubble induced turbulence BIT relations on the gas void fraction distributions, iv) studies the effect of the bubbles coalescence and breakup on bubble sizes and gas void fraction distributions. And presents the results of the simulations performed under each of these considerations.The two-way coupling process takes the effect of the dispersed phase on the continuous one through inserting source terms in the conservation equations of momentum and Turbulence. Also it modifies the volume of the computational cells in the Euler solver available for the continuous phase according to the void fraction of each cell. During the two-way coupling process, some studies needed to be performed like the adjustment of the lift force coefficient and the relation due to the change of the liquid velocity profiles as a result of the two-way coupling.The bubble-bubble collision was applied in the two-way coupling process. It was found that considering the collision appears on the void fraction distribution only in the high velocity and high gas holdup cases with very small effect. The bubble-bubble coalescence was applied as a complementary part of the collision process using the film drainage model of Chesters (1991). This model compares the film drainage time with the contact time to calculate the coalescence efficiency. The coalescence model was tested first before applying the breakup, so the bubbles size increased only and this affected on the void fraction distribution badly. Then the breakup model of Martínez-Bazán (1999a, b) was applied to perform the equilibrium in the bubble sizes. These two processes of the coalescence and breakup found to consume long computational time, the reason that did not give us a chance for testing many cases with considering both coalescence and breakup.The main investigation point through the development of this work was the BIT kinetic energy term and its effect on the used CRW model. This was considered in nearly every phase of the model development to study the effect of the BIT under the different considerations of the bubbles interaction mechanisms. It could be concluded a final vi expression for the BIT relation that is used successfully with the CRW models under consideration.vii ResumenUna nueva aproximación euleriana-lagarangiana, en su forma de acople en dos vías, para ...

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Bubble-wall interactions in a vertical gas–liquid flow: Bouncing, sliding and bubble deformations

Cited by 45 publications

References 23 publications

Near-wall rising behaviour of a deformable bubble at high Reynolds number

Near-wall rising behaviour of a deformable bubble at high Reynolds number

Air–water flow in a vertical pipe: experimental study of air bubbles in the vicinity of the wall

Coupled Lagrange-Euler Model for Simulation of Bubbly Flow in Vertical Pipes Considering Turbulent 3d Random Walks Models and Bubbles Interaction Effects

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