Modeling of bubble coalescence and break-up in turbulent bubbly flow

Mukin, Roman

doi:10.1016/j.ijmultiphaseflow.2014.02.008

Cited by 42 publications

(21 citation statements)

References 55 publications

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“…5, we also give a comparison with the calculations of [17] (2) and (3), performed using two models of bubble break-up and coalescence. The bubble concentration profile is almost uniform in the turbulent core region.…”

Section: The Results Of a Comparative Analysismentioning

confidence: 97%

“…At x/(2R) = 53.5, the calculated diameter of the bubbles is smaller than that in the experiments [35], and a shift of the balance between the break-up and coalescence towards the bubble coalescence is observed in the calculations. Apparently, this is attributable to the fact that the coalescence rate is proportional to the squared bubble concentration, while the fragmentation rate is linearly proportional to the bubble concentration [17]. This also results in the growth of the bubble size.…”

Section: The Results Of a Comparative Analysismentioning

confidence: 99%

“…This criterion determines the relation between the external forces (gravity) and the surface tension. We note that in [29] the value of the coefficient C L,k = −0.29, but, using the data from [16,17,30], we assumed that C L,k = −0.27. The coefficient in the expression for the turbulent diffusion is C T = 0.1 [10], and α k is the local gas volume fraction of the k-th group of bubbles.…”

Section: Interphase Forcesmentioning

confidence: 99%

“…The coefficient in the expression for the turbulent diffusion is C T = 0.1 [10], and α k is the local gas volume fraction of the k-th group of bubbles. The direction of the lifting force depends on the flow direction and the bubble size [10,16,17,30]. The formula for C L,k is written with account of the sign change for the bubbles whose size is greater than 5 mm.…”

Section: Interphase Forcesmentioning

confidence: 99%

“…The mass, momentum, and energy balance equations are solved for each "monodisperse" group with account of bubble coalescence and break-up, which results in the nonlinear increase in the computation time with increase in the number of the groups. In [16,17], a model is proposed and the evolution of the bubble size spectrum is modeled numerically. The model uses the approximation of a continuous distribution of the bubbles over sizes in the form of a sum of several δ -functions.…”

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confidence: 99%

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Modeling of turbulent structure of an upward polydisperse gas-liquid flow

Пахомов¹,

Терехов²

2015

Fluid Dyn

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Calculations of the structure of an upward polydisperse gas-liquid pipe flow are presented. The model is based on the Eulerian approach with account of the feedback effect of the bubbles on the average parameters and turbulence of the carrier phase. The turbulent kinetic energy of the fluid is calculated using the transport equations for the Reynolds stresses. The bubble dynamics are described with account for the variation of the mean bubble volume due to the coalescence and break-up of the bubbles. The comparison of the results with experimental data shows that the approach developed makes it possible to describe adequately turbulent gas-liquid flows over a wide range of variation of the gas volume fraction and the initial bubble size.Vertical bubbly flows are typical of chemical, nuclear, power and other branches of engineering. The information on the structure, the average and fluctuation parameters, and the cross-sectional distributions of bubbles in a channel (pipe) flow is necessary both from the fundamental and practical points of view.The complexity of the mathematical description of such flows is associated with the necessity to take into account a large number of factors of different physical nature, such as the carrier-phase turbulence, phase interaction, coalescence and fragmentation of the bubbles. A gas-liquid two-phase flow depends on the flow-rate parameters, geometry, flow regime, physical properties of the liquid and bubbles, and the bubble size [1-6]. As a rule, gas-liquid flows are polydisperse, since the bubbles usually are of different size [7-10]. When modeling these flows with account for the coalescence and break-up of the bubbles, the computational expenses are much higher than in calculating monodisperse bubbly flows. This is why different simplifying assumptions are widely used, the main of which is the monodispersity of the gas-liquid flow [1][2][3][4].To date, several methods of modeling of polydisperse two-phase flows with bubble coalescence and break-up have been developed. At the moment, one of the most informative methods of description of bubble dynamics is the Population Balance Model (PBM) [11]. This model, accomplished with the continuity and momentum equations, is widely used in the Eulerian methods [12][13][14].One of the PBM approaches is the calculation based on the decomposition of all bubbles into several classes with different size and (or) velocity [15] and modeling of each group on the basis of the multi-fluid approach. This is the MUSIG method, in which the inclusions with different sizes have the same velocity [8-10], or its modification H-MUSIG [15], in which the inclusions with different sizes have different velocities. The mass, momentum, and energy balance equations are solved for each "monodisperse" group with account of bubble coalescence and break-up, which results in the nonlinear increase in the computation time with increase in the number of the groups. In [16,17], a model is proposed and the evolution of the bubble size spectrum is modeled numerically. ...

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Section: The Results Of a Comparative Analysismentioning

confidence: 97%

Section: The Results Of a Comparative Analysismentioning

confidence: 99%

Section: Interphase Forcesmentioning

confidence: 99%

Section: Interphase Forcesmentioning

confidence: 99%

mentioning

confidence: 99%

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Modeling of turbulent structure of an upward polydisperse gas-liquid flow

Пахомов¹,

Терехов²

2015

Fluid Dyn

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Phase distribution in dispersed liquid–liquid flow in vertical pipe: Mean and turbulent contributions of interfacial force

2017

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We applied an Eulerian–Eulerian two‐fluid model on an upward dispersed oil–water flow in vertical pipe with 80 mm diameter and 2.5 m length. The numerical profiles of the radial distribution of the oil drops at 1.5 m from the inflow are compared to the experimental data of Lucas and Panagiotopoulos (Flow Meas Instrum. 2009;20:127–135) This article analyzes the roles of turbulence and interfacial forces on the phase distribution phenomenon. In liquid–liquid flow the relative velocity is low and the distribution of the dispersed phase is mainly governed by the turbulence. This work highlights the important role of the turbulent contribution obtained by averaging the added mass force on the radial distribution profiles of the oil drops. The numerical results present improved profiles of the dispersed phase comparing to the experimental data when this turbulent contribution is taken into account in the momentum balance. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4214–4223, 2017

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Computational modeling of microbubble coalescence and breakup using large eddy simulation and Lagrangian tracking

et al. 2020

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The flow of dispersed microbubbles was studied with an Eulerian-Lagrangian technique using large eddy simulation to predict the continuous liquid flow and Lagrangian tracking to compute bubble trajectories. The model fully accounts for bubble coalescence and breakup and was applied to horizontal and vertical channel flows. With low levels of turbulence, gravity in horizontal, and lift in vertical, channel flows govern the bubble spatial and collision distribution. When turbulence is sufficiently high to, at least partially, oppose bubble preferential concentration, more uniform collision and coalescence distributions are found, although these remain peaked near the wall in both configurations. Almost 100% coalescence efficiency was always found, due to bubbles colliding along similar trajectories, with breakup only recorded in a flow of low surface tension refrigerant R134a. Models like this can provide the required quantitative understanding of the microbubbles complex behavior, as well as supporting the development of more macroscopic modeling closures.

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Modeling of bubble coalescence and break-up in turbulent bubbly flow

Cited by 42 publications

References 55 publications

Modeling of turbulent structure of an upward polydisperse gas-liquid flow

Modeling of turbulent structure of an upward polydisperse gas-liquid flow

Phase distribution in dispersed liquid–liquid flow in vertical pipe: Mean and turbulent contributions of interfacial force

Computational modeling of microbubble coalescence and breakup using large eddy simulation and Lagrangian tracking

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