Asiagbe, KS orcid.org/0000-0001-6957-8597, Fairweather, M, Njobuenwu, DO orcid.org/0000-0001-6606-1912 et al. (1 more author) (2017) Large eddy simulation of microbubble transport in a turbulent horizontal channel flow. International Journal of Multiphase Flow, 94. pp. 80-93. ISSN 0301-9322
Abstract
Liquid-gas multiphase flows occur in many engineering and environmental applications, with the former ranging from the flow of oil and gas in pipelines, of steam and water in nuclear reactors and steam generators, and the evaporation and condensation of refrigerants in refrigeration and air conditioning equipment. In this paper, the dispersion and interaction between microbubbles and turbulence in a horizontal channel flow is investigated using a two-way coupled Eulerian-Lagrangian approach based on large eddy simulation. The microbubbles are considered to be spherical and non-deformable, and are represented by a Lagrangian bubble tracking technique, with the bubbles subject to drag, gravity, buoyancy, shear lift, added mass and pressure gradient forces. Dynamic calibration of a Smagorinsky-type sub-grid scale (SGS) closure is employed to account for the unresolved stresses, whilst a stochastic Markov method is used to describe the effect of the SGS velocity fluctuations on bubble dispersion. Channel flows of water at two shear Reynolds numbers, R e τ = 150 and 590, and three different bubble diameters, d b = 100 , 220 and 330 μm, are simulated. The results show acceptable agreement with DNS predictions of single- and two-phase flows, with the low density microbubbles migrating towards the upper channel wall with time under the influence of buoyancy, and segregating in the upper half of the channel, with this effect increasing with bubble diameter. The accumulated bubbles near the upper wall modify the liquid velocity field, with the mean velocity profile becoming asymmetric as a consequence and with slight modification of the turbulent stresses. At higher mean velocity and turbulence levels, the buoyancy effect is reduced due to more effective turbulent dispersion of the microbubbles, leading to reduced bubble migration towards the upper channel wall.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 Elsevier Ltd. This is an author produced version of a paper published in International Journal of Multiphase Flow. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Large eddy simulation; Eulerian-Lagrangian; microbubbles, turbulent flow, horizontal channel |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 27 Apr 2017 10:29 |
Last Modified: | 27 Apr 2018 00:38 |
Published Version: | https://doi.org/10.1016/j.ijmultiphaseflow.2017.04... |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.ijmultiphaseflow.2017.04.016 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:115728 |