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Modelling of particle fluctuations in turbulence by stochastic processes
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.ORCID iD: 0000-0002-9819-2906
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.ORCID iD: 0000-0003-3336-1462
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
(English)Manuscript (Other academic)
Identifiers
URN: urn:nbn:se:kth:diva-7989OAI: oai:DiVA.org:kth-7989DiVA: diva2:13189
Note
QC 20100726Available from: 2008-02-20 Created: 2008-02-20 Last updated: 2010-11-24Bibliographically approved
In thesis
1. Modelling of turbulent gas-particle flow
Open this publication in new window or tab >>Modelling of turbulent gas-particle flow
2008 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

An Eulerian-Eulerian model for dilute gas-particle turbulent flows is developed for engineering applications. The aim is to understand the effect of particles on turbulent flows. The model is implemented in a finite element code which is used to perform numerical simulations. The feedback from the particles on the turbulence and the mean flow of the gas in a vertical channel flow is studied. In particular, the influence of the particle response time and particle volume fraction on the preferential concentration of the particles near the walls, caused by the turbophoretic effect is explored. The study shows that the particle feedback decreases the accumulation of particles on the walls. It is also found that even a low particle volume fraction can have a significant impact on the turbulence and the mean flow of the gas. A model for the particle fluctuating velocity in turbulent gas-particle flow is derived using a set of stochastic differential equations. Particle-particle collisions were taken into account. The model shows that the particle fluctuating velocity increases with increasing particle-particle collisions and that increasing particle response times decrease the fluctuating velocity.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. viii, 24 p.
Series
Trita-MEK, ISSN 0348-467X ; 2008:01
Keyword
turbulent gas-particle flows, modelling, turbophoresis, two-way coupling
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-4639 (URN)
Presentation
2008-03-12, E2, E-huset, Lindstedtsvägen 3, Stockholm, 14:15
Opponent
Supervisors
Note
QC 20101124Available from: 2008-02-20 Created: 2008-02-20 Last updated: 2010-11-24Bibliographically approved
2. Model predictions of turbulent gas-particle shear flows
Open this publication in new window or tab >>Model predictions of turbulent gas-particle shear flows
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A turbulent two-phase flow model using kinetic theory of granularflows for the particle phase is developed and implmented in afinite element code. The model can be used for engineeringapplications. However, in this thesis it is used to investigateturbulent gas-particle flows through numerical simulations.  The feedback from the particles on the turbulence and the meanflow of the gas in a vertical channel flow is studied. In particular,the influence of the particle response time, particle volumefraction and particle diameter on the preferential concentration ofthe particles near the walls, caused by the turbophoretic effect isexplored. The study shows that when particle feedback is includedthe accumulation of particles near the walls decreases. It is also foundthat even at low volume fractions particles can have a significant impacton the turbulence and the mean flow of the gas. The effect of particles on a developing turbulent vertical upward pipeflow is also studied. The development length is found to substantiallyincrease compared to an unladen flow. To understand what governs thedevelopment length a simple estimation was derived, showing that itincreases with decreasing particle diameters in accordance with themodel simulations. A model for the fluctuating particle velocity in turbulentgas-particle flow is derived using a set of stochastic differentialequations taking into account particle-particle collisions. Themodel shows that the particle fluctuating velocity increases whenparticle-particle collisions become more important and that increasingparticle response times reduces the fluctuating velocity. The modelcan also be used for an expansion of the deterministic model for theparticle kinetic energy.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. viii, 63 p.
Series
Trita-MEK, ISSN 0348-467X ; 2010:02
Keyword
turbulent gas-particle flows, modelling, turbophoresis, two-way coupling, particle-particle collisions, numerical simulations
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-12135 (URN)978-91-7415-579-2 (ISBN)
Public defence
2010-03-29, F3, Lindstedtsvägen 26, KTH, Stockholm, 14:15 (English)
Opponent
Supervisors
Note
QC20100726Available from: 2010-03-10 Created: 2010-03-08 Last updated: 2010-07-26Bibliographically approved

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Brethouwer, GeertAmberg, Gustav

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