Bubble coalescence dynamics

Stover, Richard L.; Tobias, Charles W.; Denn, Morton M.

doi:10.1002/aic.690431002

Cited by 74 publications

(48 citation statements)

References 18 publications

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“…According to Stover et al [25] and Sides and Tobias [26] who studied bubble coalescence in traveling swarms of gas bubbles, the surface energy that is released when two bubbles coalesce causes interface velocities of 2-4 m/s followed by bubble vibration and large amplitude oscillations of the solutions (surface waves). It is highly probable that these hydrodynamic disturbances are responsible for the high log k/log V g slope at high oxygen discharge rates.…”

Section: Methodsmentioning

confidence: 99%

Intensification of Rate of Diffusion Controlled Reactions in a Parallel Plate Electrochemical Reactor Stirred by a Curtain of Electrochemically Generated Gas Bubbles

Sedahmed

Nirdosh

2007

Chem Eng & Technol

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Rates of mass transfer were measured at a vertical plate stirred by a rising curtain of oxygen bubbles generated electrochemically at an upstream plate by measuring the limiting current of the cathodic reduction of K 3 Fe(CN) 6 in alkaline solution. The rate of mass transfer was found to increase over the natural convection value by a factor ranging from 2.4 to 25 compared to the previously reported range of 2-5 in the case of copper deposition from acidified solutions. The high tendency of oxygen bubbles to coalesce in alkaline solutions is believed to be responsible for the high rates of mass transfer in alkaline solutions. The rate of mass transfer at a plate stirred by a curtain of oxygen bubbles was found to decrease with increasing plate height and electrolyte concentration. Curtains of H 2 bubbles were found to be less effective in enhancing the rate of mass transfer compared to that of oxygen. Practical application of the results in designing a modified parallel plate electrochemical reactor stirred by a counterelectrode gas curtain was highlighted. The suggested design has the potential of saving part or all of the mechanical stirring energy as well as floor space since it extends vertically.

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Section: Methodsmentioning

confidence: 99%

Intensification of Rate of Diffusion Controlled Reactions in a Parallel Plate Electrochemical Reactor Stirred by a Curtain of Electrochemically Generated Gas Bubbles

Sedahmed

Nirdosh

2007

Chem Eng & Technol

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“…There has been a long history of studying the bubble coalescence mechanisms through experiments 22,23 and theoretical modeling 24 . These early research focused on ideal, stagnant, and millimeter-sized bubbles in free spaces.…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal scaling of unequal microbubble coalescence

Chen

Zhu

et al. 2016

AIChE Journal

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We numerically study coalescence of air microbubbles in water, with density ratio 833 and viscosity ratio 50.5, using lattice Boltzmann method. The focus is on the effects of size inequality of parent bubbles on the interfacial dynamics and coalescence time. Twelve cases, varying the size ratio of large to small parent bubble from 5.33 to 1, are systematically investigated. The "coalescence preference", coalesced bubble closer to the larger parent bubble, is well observed and the captured power-law relation between the preferential relative distance χ and size inequality γ, χ ∼ γ −2.079 , is consistent to the recent experimental observations. Meanwhile, the coalescence time also exhibits power-law scaling as T ∼ γ −0.7 , indicating that unequal bubbles coalesce faster than equal bubbles.Such a temporal scaling of coalescence on size inequality is believed to be the first-time observation as the fast coalescence of microbubbles is generally hard to be recorded through laboratory experimentation.

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“…[7][8][9][10][14][15][16][17][18] Direct imaging of slower and larger macroand micro-bubbles employed different cameras and light sources. 13,[46][47][48][49][50][51][52] There is a possibility of using a continuous light source and of capturing a short transient NB with highspeed image detectors. [53][54][55][56][57] However that would require a nanosecond gating speed, sub-micron spatial resolution, and the corresponding high optical sensitivity.…”

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confidence: 99%

Experimental techniques for imaging and measuring transient vapor nanobubbles

Lukianova‐Hleb

Lapotko

2012

Applied Physics Letters

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Imaging and measuring transient vapor bubbles at nanoscale pose certain experimental challenges due to their reduced dimensions and lifetimes, especially in a single event experiment. Here, we analyze three techniques that employ optical scattering and acoustic detection in identifying and quantifying individual photothermally induced vapor nanobubbles (NBs) at a wide range of excitation energies. In optically transparent media, the best quantitative detection can be achieved by measuring the duration of the optical scattering time-response, while in an opaque media, the amplitude of the acoustic time-response well describes NBs in the absence of stress waves. Transient thermal evaporation and the generation of vapor bubbles are one of the basic processes accompanying non-stationary high-temperature heat-and mass-transfer in liquids. The science and the methods for the detection of inertial vapor bubbles of various origins were well developed for macro-and micro-sized bubbles and mainly employ their ability to emit pressure and to scatter the incident light. Recent developments in nanoscience reduced the spatial and temporal scale of vapor bubbles to nanometers and nanoseconds. [7][8][9][10]23,[27][28][29][30][31][32][33] Unlike their larger analogs, vapor nanobubbles (NBs) require much higher sensitivity and resolution of the detection methods for their imaging, quantification, and identification among other phenomena, such as transient heating and the generation of stress waves. Here, we analyze several experimental techniques for the imaging and quantitative analysis of transient vapor nanobubbles as single events and we troubleshoot some related errors. Due to the multiple biomedical applications of NBs and related phenomena, [34][35][36][37][38] it should be noted that we consider the transient events, but not the materials (particles) that are often also called nanobubbles.39, 40 We also do not consider the cavitation of preexisting bubbles that is well studied elsewhere. 41 While NBs may have various sources of energy (the heating of liquid above the boiling threshold, local rarefaction, and plasma discharge), we employed an experimental model of a single NB in water. Such a model provides maximal precision, control, and reproducibility in NB generation through the localized transient photothermal heating of liquid above the evaporation point. This was achieved through the optical excitation of individual 60 nm gold nanospheres in water with single short laser pulses (70 ps and 532 nm) at specific fluences above the NB generation threshold. We used the plasmonic conversion of optical energy into heat to control the maximal diameter and lifetime of the NBs through the fluence of a single laser pulse, as described in detail previously. [8][9][10]33 This experimental model includes an internal metal nanoparticle (NP) that acts as the source of the bubble energy during bubble generation and prevents the development of extreme temperatures and sonoluminescence at the collapse stage, 8,42 unlike "classical" bu...

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Bubble coalescence dynamics

Cited by 74 publications

References 18 publications

Intensification of Rate of Diffusion Controlled Reactions in a Parallel Plate Electrochemical Reactor Stirred by a Curtain of Electrochemically Generated Gas Bubbles

Intensification of Rate of Diffusion Controlled Reactions in a Parallel Plate Electrochemical Reactor Stirred by a Curtain of Electrochemically Generated Gas Bubbles

Spatial and temporal scaling of unequal microbubble coalescence

Experimental techniques for imaging and measuring transient vapor nanobubbles

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