Turbulence Modulation by Small Bubbles in the Vertical Upward Channel Flow

Pang, Mingjun; Wei, Jinjia; Yu, Bo

doi:10.1155/2013/379839

Cited by 6 publications

(7 citation statements)

References 25 publications

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“…A number of these, such as the experiments presented by Hosokawa et al and the numerical simulations of Ervin and Tryggvason and Pang et al, focused on the dispersion of bubbles and their complex interactions with the turbulent flow structures. Pang et al investigation of a channel flow demonstrated that the liquid phase turbulence is intensified near the walls and slightly weakened in the central region due to bubble addition. Giusti et al used one‐way coupled numerical simulations to study the effect of the lift force on the behavior of nondeformable microbubbles dispersed in a turbulent vertical channel flow.…”

Section: Introductionmentioning

confidence: 99%

“…Although DNS resolves all the scales of a flow, and provides results comparable to those available from experimental studies, its computational cost means that it is still restricted to the simulation of relatively few bubbles, particularly when coupled with interface tracking techniques to resolve bubble motion, and low Reynolds number flows. Even when coupled to a Lagrangian methodology that allowed the tracking of significant numbers of bubbles (approximately several hundred thousands), DNS studies in closed ducts have been mostly limited to 150–200 shear Reynolds number flows . Instead LES, where the large scales of turbulent motion are resolved while the subgrid turbulent scales and their effect on the mean flow are modeled, allows complex flows with industrial relevance to be predicted more readily.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

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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“…Prediction of population balance approaches and the accuracy of coalescence and breakup models strongly depends on turbulence in the continuous field and the turbulence modelling approach used to predict it [9]. In previous studies, turbulence modulation in bubbly flows due to the dispersed bubbles has been widely discussed and analysed by comparing turbulence statistics for different bubble sizes and properties [13][14][15]. However, detailed analysis of the impact of turbulence on four-way coupled simulations and predictions of the models used to account for bubble coalescence and breakup have rarely been performed.…”

Section: Introductionmentioning

confidence: 99%

Microbubble coalescence and breakup in turbulent vertical channel flows

Asiagbe

Fairweather

Njobuenwu

et al. 2018

Proceeding of THMT-18. Turbulence Heat and Mass Transfer 9 Proceedings of the Ninth International Symposium on Turbulence Heat

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Large eddy simulation coupled to Lagrangian bubble tracking is used to study four-way coupled turbulent bubbly flow in channels, including bubble collision, coalescence and breakup. Upward and downward vertical channel flows of water at shear Reynolds numbers of 150 and 2000 are examined, with air bubbles of diameter = 220 m dispersed within the flows. Additional simulations are performed for the case of refrigerant R134a at a shear Reynolds number of 1154. The ability of the model to predict coalescence and breakup is evaluated, as well as the impact of the flow condition on the two phenomena. Coalescence and breakup are favoured in upflow conditions, with turbulence found to significantly impact the level of bubble interaction. Coalescence is dominant at low turbulence levels and breakup, which was only detected in the R134a flow, is favoured at high turbulence. The results demonstrate the capabilities of the overall model to predict bubble coalescence and breakup, and its usefulness for predicting flows that are of industrial relevance where interfacial area and bubble size distribution govern interfacial mass, momentum and heat transfer processes.

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“…Experimental investigations had been conducted by researchers [4][5][6][7][8][9]. Numerical studies had also been carried out by researchers [10][11][12][13][14][15][16][17][18]. Kim et al [19] conducted theoretical analyses on the liquid turbulence modulation by microbubbles.…”

Section: Introductionmentioning

confidence: 99%

Study on Liquid Turbulence Modulation by Microbubbles in Different Turbulence Layers

Pang

Wei

2014

Advances in Mechanical Engineering

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Bubbly flows exist extensively in industrial processes. To enhance efficiencies of industrial processes, it is very necessary and important to understand detailedly mechanisms of liquid turbulence modulation by bubbles. To understand mechanisms of the liquid turbulence modulation by microbubbles, an Euler-Lagrange two-way model was used to investigate and analyze deeply the liquid turbulence modulation by microbubbles in the subviscous, buffer, and outer layers, respectively. The present results show that the liquid turbulence modulation by microbubbles is related to microbubble locations; the liquid turbulence is intensified when microbubbles are in the outer layers, whereas the liquid turbulence is suppressed when microbubbles are in the subviscous and buffer layer; and the drag reduction occurs only when microbubbles are in the buffer layer.

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Turbulence Modulation by Small Bubbles in the Vertical Upward Channel Flow

Cited by 6 publications

References 25 publications

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

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

Microbubble coalescence and breakup in turbulent vertical channel flows

Study on Liquid Turbulence Modulation by Microbubbles in Different Turbulence Layers

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