Interaction of two oscillating bubbles rising in a thin-gap cell: vertical entrainment and interaction with vortices

Filella, Audrey; Ern, Patricia; Roig, Véronique

doi:10.1017/jfm.2020.4

Cited by 14 publications

(7 citation statements)

References 32 publications

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“…For an unstable confined bubble, the dynamics of the wake has been characterized in previous works by two major features: the non-material line of maximal velocity in the wake and the released vorticity. They have been obtained up to now by 2D2C-PIV measurements (Filella et al 2015) and proved to be pertinent to model bubble-bubble interactions (Filella et al 2020). At a given time step t, the spatial evolution of the ascending flow behind the bubble can be characterized by the position x v max (y, t) corresponding to the maximal value v max of the norm of the liquid velocity for each longitudinal position y.…”

Section: Comparison Of Averaged Velocity Fields Past the Bubble Issued From The Stb And 2d2c-piv Methodsmentioning

confidence: 99%

Exploration by Shake-the-Box technique of the 3D perturbation induced by a bubble rising in a thin-gap cell

et al. 2021

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Section: Comparison Of Averaged Velocity Fields Past the Bubble Issued From The Stb And 2d2c-piv Methodsmentioning

confidence: 99%

Exploration by Shake-the-Box technique of the 3D perturbation induced by a bubble rising in a thin-gap cell

et al. 2021

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“…Indeed, these final instants of the interaction process, based on the wake entrainment mechanism, lead to bubble collision when the interacting bubbles are large enough to deform (Miyahara, Tsuchiya & Fan 1991). In contrast, smaller bubbles that barely deform and respond faster to the liquid velocity fluctuations can eventually avoid the collision (Filella, Ern & Roig 2020).…”

Section: Determination and Analysis Of The Bubble Pair Collision Freq...mentioning

confidence: 99%

Coalescence of bubbles in a high Reynolds number confined swarm

et al. 2022

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We investigate experimentally the coalescence cascade process for a confined swarm of deformable bubbles immersed in a bidimensional vertical cell filled with water. For different gas volume fractions, air bubbles of size $D_0$ larger than the cell thickness are injected at the bottom of the cell. The bubbles swarms transformation is explored using high-speed visualizations. The time evolution of each bubble in the swarm is determined using a specifically developed algorithm, enabling bubble tracking and coalescence detection. We determine the evolution of the bubble size distribution downstream from the injection point, and show that the stages of the coalescence cascade are characterized by the diameter, $D_{V90}$ , representative of the largest bubbles. The collision frequency of pairs of bubbles of sizes $D_k$ and $D_{k'}$ , $h(D_k, D_{k'})$ , and their coalescence efficiency, $\lambda$ , are obtained from the experiments. The efficiency is nearly constant, independently of the bubble sizes and of the gas volume fraction. Concerning collision frequency, our results reveal the existence of two different coalescence regimes depending on the capability of the bubbles to deform. Models describing $h(D_k, D_{k'})$ for both regimes are provided. They take into account the specific response of the bubble pair, which depends on the reduced diameter $D_p = 2 D_k D_{k'} / (D_k + D_{k'})$ , to the global swarm-induced agitation governed by $D_{V90}$ and the gas volume fraction. In the first regime, occurring for smaller $D_p$ , bubbles are brought together by agitation and rapidly coalesce, while for sufficiently large $D_p$ , both bubbles are able to deform and spend more time adapting mutually their shapes before coalescing.

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“…However, all these studies considered Reynolds numbers of which belong to the moderately inertial regime examined numerically by Part 1 and, independently but with the same code, by Kusuno & Sanada (2021). A noticeable exception is the work of Filella, Ern & Roig (2020) in which wake interactions behind two bubbles rising in a thin-gap cell were scrutinized using time-resolved particle image velocimetry. However, the corresponding two-dimensional dynamics makes the problem barely comparable to the three-dimensional configuration of interest here.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional dynamics of a pair of deformable bubbles rising initially in line. Part 2. Highly inertial regimes

Zhang

Magnaudet

2022

J. Fluid Mech.

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The buoyancy-driven dynamics of a pair of gas bubbles released in line is investigated numerically, focusing on highly inertial conditions under which isolated bubbles follow non-straight paths. In an early stage, the second bubble always drifts out of the wake of the leading one. Then, depending on the ratios of the buoyancy, viscous and capillary forces which define the Galilei ( $Ga$ ) and Bond ( $Bo$ ) numbers of the system, five distinct regimes specific to such conditions are identified, in which the two bubbles may rise independently or continue to interact and possibly collide in the end. In the former case, they usually perform large-amplitude planar zigzags within the same plane or within two distinct planes, depending on the oblateness of the leading bubble. However, for large enough $Ga$ and low enough $Bo$ , they follow nearly vertical paths with small-amplitude erratic horizontal deviations. Increasing $Bo$ makes the wake-induced attraction toward the leading bubble stronger, forcing the two bubbles to realign vertically one or more times along their ascent. During such sequences, wake vortices may hit the trailing bubble, deflecting its path and, depending on the case, promoting or hindering further possibilities of interaction. In some regimes, varying the initial distance separating the two bubbles modifies their lateral separation beyond the initial stage. Similarly, minute initial angular deviations favour the selection of a single vertical plane of rise common to both bubbles. These changes may dramatically affect the fate of the tandem as, depending on $Bo$ , they promote or prevent future vertical realignments.

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Interaction of two oscillating bubbles rising in a thin-gap cell: vertical entrainment and interaction with vortices

Cited by 14 publications

References 32 publications

Exploration by Shake-the-Box technique of the 3D perturbation induced by a bubble rising in a thin-gap cell

Exploration by Shake-the-Box technique of the 3D perturbation induced by a bubble rising in a thin-gap cell

Coalescence of bubbles in a high Reynolds number confined swarm

Three-dimensional dynamics of a pair of deformable bubbles rising initially in line. Part 2. Highly inertial regimes

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