A note on gas bubble formation models

LaNauze, R.D.; Harris, I. J.

doi:10.1016/0009-2509(74)87020-x

Cited by 22 publications

(9 citation statements)

References 7 publications

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“…From the above equation, the gravitational Bond number is found to be 0.41. On the basis of previous research, 44,45 the forces that affect the pendant ferrofluid balance during the formation of a droplet. Thus, the sum of the gravity and the magnetic forces should be equal to the force induced by the interfacial tension during the formation of the ferrofluid droplet by the DC-MF.…”

Section: ■ Physics Of Droplet Formationmentioning

confidence: 99%

“…On the basis of previous research, , the forces that affect the pendant ferrofluid balance during the formation of a droplet. Thus, the sum of the gravity and the magnetic forces should be equal to the force induced by the interfacial tension during the formation of the ferrofluid droplet by the DC-MF. The magnetic susceptibility follows the Langevin law as a function of field strength ( ), where H , M s , and χ 0 are the magnetic field strength, ferrofluid’s saturation magnetization, and initial magnetic susceptibility, respectively.…”

Section: Physics Of Droplet Formationmentioning

confidence: 99%

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Experimental Investigation on the Dynamics of On-Demand Ferrofluid Drop Formation under a Pulse-Width-Modulated Nonuniform Magnetic Field

Bijarchi

2020

Langmuir

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Drop formation has been the focus of many studies because of its vast application in biomedicine and engineering, as well as its rich underlying physics. Applying a magnetic force on ferrofluids can provide more control over the formation process of the droplet. In this study, a time-dependent, nonuniform magnetic field was used for the formation of ferrofluid droplets using a nozzle. A pulse-width-modulation signal (PWM) was utilized to induce the time-dependent magnetic field, and a drop-on-demand system was designed using the capability of the PWM magnetic field. Three kinds of drop formation regimes under the PWM magnetic field were seen. Also, a new droplet generation regime was observed in which the drop is formed while it bounces back to the nozzle during the off-time period of the magnetic excitation. As compared to other techniques, the main advantage of droplet formation in this regime is that there will be no satellite droplet during the pinch-off. The regime map of drop formation based on the magnetic Bond number and the dimensionless induced frequency was obtained. Also, the effect of the duty cycle, the induced frequency, the magnetic induction, and the vertical interval between the coil's top surface and the nozzle on the drop formation evolution, the equivalent diameter of the droplets, the frequency of droplet formation, and the pulses that are necessary to form a drop was studied. Additionally, it was illustrated that by prolonging the duty cycle, the magnetic induction, or by decreasing the induced frequency, the equivalent diameter of the drop and the pulses that are necessary to form a drop reduce, while the frequency of drop formation increases. Eventually, a correlation for predicting the nondimensionalized diameter of the droplet, based on dimensionless variables, was presented with a maximum relative error of 8.1% and an average relative error equal to 2.2%.

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Section: ■ Physics Of Droplet Formationmentioning

confidence: 99%

Section: Physics Of Droplet Formationmentioning

confidence: 99%

Experimental Investigation on the Dynamics of On-Demand Ferrofluid Drop Formation under a Pulse-Width-Modulated Nonuniform Magnetic Field

Bijarchi

2020

Langmuir

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“…After a review of the main study, both experimental and modeling, for bubble size prediction published in the literature, ,,,,− the Geary and Rice model was chosen and implemented in Fortran code …”

Section: Resultsmentioning

confidence: 99%

Investigation into Bubble Size Distribution and Transient Evolution in the Sparger Region of Gas−Liquid External Loop Airlift Reactors

Chen

Zhao

et al. 2009

Ind. Eng. Chem. Res.

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It is well-known that the gas sparger can play an important role on the transient evolution of bubbles and bubble size distribution (BSD) in gas-liquid external loop airlift reactors (EL-ALRs). Therefore, the main subject of the present work was to study the influence of sparger design and process parameters on the transient evolution of bubbles and bubble size distribution (BSD) in the sparger region of the considered EL-ALRs. For this purpose, both detailed measurements and prediction of the size of bubbles produced at the sparger were carried out in EL-ALRs with different size and sparger structure parameters. The unique set of BSD curves were obtained by analyzing a large amount of bubbles with a measurement based on an image analysis technique. Additionally, Colella's model of BSD evolution in bubble columns was further developed by implementing a detailed physical model for predicting the initial BSD at the sparger applied to gas-liquid EL-ALRs where the model input is only based on design/process parameters. A validation of the model was carried out using data from gas-liquid EL-ALRs with different size and sparger design parameters. In order to provide more deep insight for transient evolution of bubbles at the local scale in the sparger region, the computational fluid dynamics (CFD) code Fluent 6.2 was used. The transient evolution of bubbles was simulated in the sparger region of gas-liquid EL-ALR. The simulating results of bubble size are in good agreement at the lower gas velocity with the experimental data in the sparger regions of TU-A and TU-B. With increasing gas flow rate, the difference between simulations and experimental values for bubble size increases. The simulations underestimate bubble size at high gas flow rate.

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“…In spite of the deviation from the physical situation, the spherical bubble formation model is still used to model some problems, such as the work of Yang et al 13 . Therefore, the present study revises the proposed model of Davidson 2,3 , due to some fundamental physical weaknesses in Kumar's Model 7 . A bubble volume was calculated as a sphere in the present study, instead of a spherical segment above the ori ce proposed by Lanauze and Harris 14 .…”

Section: Numerical Approachmentioning

confidence: 87%

“…There are two kinds of bubble forma-tion models according to the bubble growth shape. The rst group is the spherical bubble formation model based on an assumption of spherical bubble growth, such as the models proposed by Davidson and Schüler 2,3 , and Kumar et al [4][5][6] However, the bubble detachment criterion of the spherical bubble formation model has not been justi ed 7 . The second group includes the non-spherical models such as those proposed by Marmur and Rubin 8 as well as Pinczewski 9 .…”

Section: Introductionmentioning

confidence: 99%