Large eddy simulation of microbubble transport in a turbulent horizontal channel flow

Asiagbe, Kenneth S.; Fairweather, Michael; Njobuenwu, Derrick O.; Colombo, Marco

doi:10.1016/j.ijmultiphaseflow.2017.04.016

Cited by 19 publications

(15 citation statements)

References 51 publications

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“…The present work mainly focuses on the extension of the previous model to four‐way coupling (two‐way coupling plus bubble collision, coalescence and breakup) and associated results. Validation of the model has been previously obtained for single‐phase, one‐way and two‐way coupled simulations in both horizontal and vertical channels 20,36 …”

Section: Numerical Modelingmentioning

confidence: 99%

“…At the same time, the reduced computational effort that results from modeling, rather than simulating, the small‐scale turbulent fluctuations makes it possible to extend the methods' applicability to turbulent flows closer to conditions that are of industrial interest. In previous works, we have applied a similar approach to two‐way coupled horizontal, 36 and upward and downward vertical, channel flows, 20 addressing the interactions between the fluid and the microbubbles, and feedback of the bubbles to the turbulence in the fluid phase. In this work, the model is extended to four‐way coupled flows (two‐way coupled plus bubble collision, coalescence and breakup) by accounting for interactions between the bubbles, and bubble coalescence and breakup.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Numerical Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…Hereafter, they proposed an alternative discrete formulation of the PBE for the binary breakup, which is better than previous models made by Kumar and Ramkrishna [36]. A large-eddy simulation of microbubble transport in a turbulent horizontal channel flow was performed by Asiagbe et al [37], and the results showed that low-density microbubbles migrated towards the upper channel wall under the driven of buoyancy.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study on Flow Resistance and Bubble Transport in a Helical Static Mixer

2020

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Flow resistance and bubble transport in a helical static mixer were studied experimentally and numerically. The inline mixer increases the volume fraction of gas in liquids by breaking bubbles into smaller sizes with a micrometer size in the flow experiments. The gas–liquid flow was simulated by a combination of computational fluid dynamics and Taylor expansion methods of moments. The friction factor of the helical static mixer is much smaller than that of the Kenics static mixers. The pressure drop increases with the Reynolds number, and the increment is larger when the Reynolds number is higher. The equidistant pressure drop increases with the argument of Reynolds number, and increases when the pitch decreases from upstream to downstream. The energy expenditure increases significantly when the variable-pitch coefficient is too small. The bubble geometric mean diameter decreases and the geometric standard deviation increases when the gas–liquid fluid flows through the mixer. The variable pitch structure enhances the bubble breakup effectively. The change of the bubble size decreases with the argument of the Reynolds number. The effect of the mixer has a limitation on breaking the bubbles.

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“…Numerical modeling, therefore, has a complementary role in understanding the dynamics of bubbly flows. Normally, the carrier fluid is treated as the continuous phase, with the bubbles considered as the dispersed or discrete phase, with Eulerian–Eulerian, Eulerian–Lagrangian, and fully resolved approaches adopted. Discussions of the relative merits and disadvantages of each of these approaches are available elsewhere .…”

Section: Introductionmentioning

confidence: 99%

“…In a liquid–gas turbulent flow, the large‐scale turbulent structures interact with the bubbles and are responsible for the macroscopic bubble motion, while small‐scale turbulent structures only captured in LES, and the less energetic small scales are approximated using a subgrid‐scale (SGS) model, coupling of bubble tracking technique and LES can in principle reproduce the large scale motion responsible for the bubble motion. In our previous works, an LES Eulerian–Lagrangian model was successfully applied to horizontal channel flows and its initial application to a vertical channel flow was investigated . In these studies, LES was demonstrated to achieve a level of detail sufficient to predict bubbly flows with accuracy.…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation of microbubble dispersion and flow field modulation in vertical channel flows

et al. 2019

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Turbulent liquid–gas vertical channel flows laden with microbubbles are investigated using large eddy simulation (LES) two‐way coupled to a Lagrangian bubble tracking technique. Upward and downward flows at shear Reynolds numbers of Re τ = 150 and 590 are analyzed for three different microbubble diameters of 110, 220, and 330 μm. Predicted results are compared with published direct numerical simulation results although, with respect to comparable studies available in the literature, the range of bubble diameters and shear Reynolds numbers considered herein is extended to larger values. Microbubble concentration profiles are analyzed, with the microbubbles segregating at the wall in upflow conditions and moving toward the channel centre in downflow. The various forces acting on the bubbles, and the effect of the flow turbulence on the bubble concentration, are considered and quantified. Overall, the results suggest that the level of detail achievable with LES is sufficient to predict the fluid structures impacting bubble behavior. Therefore, LES coupled with Lagrangian bubble tracking shows promise for enabling the reliable prediction of bubble‐laden flows that are of industrial relevance. © 2018 American Institute of Chemical Engineers AIChE J, 65: 1325–1339, 2019

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Large eddy simulation of microbubble transport in a turbulent horizontal channel flow

Abstract: This is a repository copy of Large eddy simulation of microbubble transport in a turbulent horizontal channel flow.

Cited by 19 publications

References 51 publications

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

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

Experimental and Numerical Study on Flow Resistance and Bubble Transport in a Helical Static Mixer

Large eddy simulation of microbubble dispersion and flow field modulation in vertical channel flows

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