Mortimer, L, Fairweather, M and Njobuenwu, DO orcid.org/0000-0001-6606-1912 (2017) Particle concentration and stokes number effects in multi-phase turbulent channel flows. In: Particles 2017: V International Conference on Particle-based Methods. Fundamentals and Applications. 5th International Conference on Particle-Based Methods (Particles 2017), 26-28 Sep 2017, Hannover, Germany. International Center for Numerical Methods in Engineering , pp. 859-869. ISBN 9788494690976
Abstract
This investigation examines the effect that particle concentration has on the dynamics of two-phase turbulent channel flows at low and high density ratios. In the literature, little explanation is offered for the existence of high particle turbulence intensities in the buffer layer and viscous sublayer for particles with high Stokes number. The present study aims to explore particle dynamics in those regions. The spectral element method DNS solver, Nek5000, is used to model the fluid phase at a shear Reynolds number Re=, Particles are tracked using a Lagrangian approach with inter-phase momentum exchange (two-way coupling). Mean fluid and particle velocity statistics are gathered and analysed to determine the effect of increasing both Stokes number and concentration. Results indicate that the system with the greater Stokes number (air) has a much larger impact on the mean streamwise velocity and turbulence intensity profiles. As the concentration is increased, the mean flow velocity and turbulence intensity are reduced in the bulk and increased very close to the wall. For the low Stokes system, there is negligible effect on the flow statistics at low concentration. One-way coupled solid-phase statistics indicate that particles in water follow the flow very closely. At the higher densityratio, particles lag behind the flow in the bulk, but overtake the flow in the near-wall region, where the existence of increased streamwise turbulence intensities is also observed. To elucidate the dynamics, concentrations and fluxes are analysed. Particles are observed to be distributed more densely close to the wall in air, compared to a reasonably uniform distribution in water. Finally, contour plots indicate that particles in air tend to congregate in regions of low streamwise fluid velocity, and the extent to which this differs between the two systems is then quantitatively measured.
Metadata
Item Type: | Proceedings Paper |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This is an author produced version of a paper published in the proceedings of Particles 2017: V International Conference on Particle-based Methods. Fundamentals and Applications. |
Keywords: | Direct numerical simulation, Lagrangian particle tracking, Particle-laden flow, Fluid dynamics, Concentration, Stokes number |
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: | 01 Mar 2018 12:37 |
Last Modified: | 01 Mar 2018 12:41 |
Published Version: | http://congress.cimne.com/particles2017/frontal/do... |
Status: | Published |
Publisher: | International Center for Numerical Methods in Engineering |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:128010 |