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dc.contributor.author
Baker, Lucia J.
dc.contributor.author
Coletti, Filippo
dc.date.accessioned
2021-08-31T06:27:18Z
dc.date.available
2021-08-30T16:45:29Z
dc.date.available
2021-08-31T06:27:18Z
dc.date.issued
2021-02-10
dc.identifier.issn
0022-1120
dc.identifier.issn
1469-7645
dc.identifier.other
10.1017/jfm.2020.934
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/503118
dc.description.abstract
We study the dynamics of dilute, slightly negatively buoyant, millimetre-size spherical particles fully suspended in a smooth-wall open channel flow. The Reynolds number is Reτ=570 and the particle Stokes number is St+=15. Particle image velocimetry and tracking are used to obtain simultaneous, time-resolved flow fields and particle trajectories. Particles travel at a lower mean velocity than the fluid: in the log layer this is due to the oversampling of slow fluid regions, but closer to the wall the cause is instantaneous slip between particles and fluid. The particle Reynolds stresses exceed those of the fluid. Near the wall, the particle streamwise diffusivity is larger than the momentum diffusivity, while the opposite is true for the wall-normal component. The particle transport is strongly linked to ejections, while the role of sweeps is marginal, and there is no evidence of turbophoresis. The concentration profile follows a power law with a shallower slope than predicted by equilibrium theories that neglect particle inertia. Upward-/downward-moving particles display positive/negative mean streamwise acceleration due to the particle–fluid slip. The particles that contact the wall are faster than the local fluid both before reaching the wall and after leaving it. Therefore, they are decelerated by drag and pushed downward by shear-induced lift. The durations of wall contact follow exponential distributions with characteristic time scale close to the particle response time. Lift-offs coincide with particles meeting a fluid ejection. These observations emphasize the competing effects of inertia and gravity.
en_US
dc.language.iso
en
en_US
dc.publisher
Cambridge University Press
en_US
dc.title
Particle–fluid–wall interaction of inertial spherical particles in a turbulent boundary layer
en_US
dc.type
Journal Article
dc.date.published
2020-12-11
ethz.journal.title
Journal of Fluid Mechanics
ethz.journal.volume
908
en_US
ethz.journal.abbreviated
J. Fluid Mech.
ethz.pages.start
A39
en_US
ethz.size
35 p.
en_US
ethz.publication.place
Cambridge
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02628 - Institut für Fluiddynamik / Institute of Fluid Dynamics::09709 - Coletti, Filippo / Coletti, Filippo
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02628 - Institut für Fluiddynamik / Institute of Fluid Dynamics::09709 - Coletti, Filippo / Coletti, Filippo
en_US
ethz.date.deposited
2021-08-30T16:45:35Z
ethz.source
FORM
ethz.eth
no
en_US
ethz.availability
Metadata only
en_US
ethz.rosetta.installDate
2021-08-31T06:27:25Z
ethz.rosetta.lastUpdated
2021-08-31T06:27:25Z
ethz.rosetta.versionExported
true
ethz.COinS
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