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Model predictions of turbulent gas-particle shear flows
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
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 [en]
turbulent gas-particle flows, modelling, turbophoresis, two-way coupling, particle-particle collisions, numerical simulations
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-12135ISBN: 978-91-7415-579-2 (print)OAI: oai:DiVA.org:kth-12135DiVA: diva2:302591
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
List of papers
1. Modelling of turbulent gas-particle flows with focus on two-way coupling effects on turbophoresis
Open this publication in new window or tab >>Modelling of turbulent gas-particle flows with focus on two-way coupling effects on turbophoresis
2012 (English)In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 224, 36-45 p.Article in journal (Refereed) Published
Abstract [en]

An Eulerian model was developed for turbulent gas-particle flow that takes into account the influence of particles on the gas-phase turbulence. For the description of the particle-phase stress the kinetic theory of granular flow and the simpler Hinze model were adopted. A K-ω model was used as the gas phase turbulence model. The difference between one- and two-way coupling was investigated for different particle volume fractions and particle diameters. It was found that particles with a much higher density than the fluid substantially affect the gas-phase in turbulent channel flow for particle volume fractions as low as 10 -4. The models with the particle-phase stress described by the kinetic theory of granular flow and the simpler Hinze model produce similar results for particles with small response times but deviate for larger response times. The study shows that two-way coupling and the turbophoretic effect must be taken into account in models even at relatively low particle volume fractions.

Keyword
Concentration profiles, Fluid mechanics and transport phenomena, Modelling, Turbophoresis, Turbulent gas-particle flows, Two-way coupling
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-7988 (URN)10.1016/j.powtec.2012.02.017 (DOI)000304792000005 ()2-s2.0-84860504866 (Scopus ID)
Funder
Swedish e‐Science Research Center
Note

QS 20120529. Updated from submitted to published.

Available from: 2008-02-20 Created: 2008-02-20 Last updated: 2013-04-08Bibliographically approved
2. A study of particle feedback in turbulent gas-particle flows
Open this publication in new window or tab >>A study of particle feedback in turbulent gas-particle flows
2009 (English)In: A study of particle feedback in turbulent gas-particle flows / [ed] K. Hanjalic, Y. Nagano, S. Jakirlic, New York, Wallingford (UK): Begell House Inc. , 2009, 713-716 p.Conference paper, Published paper (Refereed)
Abstract [en]

The upward turbulent gas-particle flow in a channel was studied usingan Eulerian-Eulerian two-phase model taking into account the feedbackfrom the particles on the gas-phase. The objective is to study theinfluence of particles with different diameters and volume fractionson the flow and particularly on the accumulation of particles in thenear wall region due to the turbophoretic effect. The results wereobtained with a two-phase flow model that is presented. Theaccumulation of particles in the near-wall region was found to bestrongest for particles with τp+ = 13. The model also shows thatvarying the particle diameters leads to different feedback of theparticles on the turbulent flow.

Place, publisher, year, edition, pages
New York, Wallingford (UK): Begell House Inc., 2009
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-12127 (URN)978-1-56700-262-1 (ISBN)
Conference
Sixth International Symposium On Turbulence, Heat and Mass Transfer
Note
QC20100726Available from: 2010-03-08 Created: 2010-03-08 Last updated: 2010-07-26Bibliographically approved
3. A modelling study of evolving particle-laden turbulent pipe-flow
Open this publication in new window or tab >>A modelling study of evolving particle-laden turbulent pipe-flow
2011 (English)In: Flow Turbulence and Combustion, ISSN 1386-6184, E-ISSN 1573-1987, Vol. 86, no 3-4, 477-495 p.Article in journal (Refereed) Published
Abstract [en]

An Eulerian turbulent two phase flow model using kinetic theory ofgranular flows for the particle phase was developed in order to studyevolving upward turbulent gas particle flows in a pipe. Themodel takes the feedback of the particles into account and its resultsagree well with experiments. Simulations show that the pipe length required for particle laden turbulent flow to become fully developed is up to five times longer than an unladen flow. To increase theunderstanding of the dependence of the development length on particlediameter a simple model for the expected development length wasderived. It shows that the development length becomes shorter forincreasing particle diameters, which agrees with simulations up to aparticle diameter of 100 μm. Thereafter the development lengthbecomes longer again for increasing particle diameters because largerparticles need a longer time to adjust to the velocity of the carrierphase.

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-12131 (URN)10.1007/s10494-011-9335-2 (DOI)000289210700009 ()2-s2.0-79955899672 (Scopus ID)
Funder
Swedish e‐Science Research Center
Note
QC 20110516Available from: 2010-03-08 Created: 2010-03-08 Last updated: 2012-05-24Bibliographically approved
4. Numerical computation of turbulent gas-particle flow in a backward-facing step. Model comparison with experimental data.
Open this publication in new window or tab >>Numerical computation of turbulent gas-particle flow in a backward-facing step. Model comparison with experimental data.
Show others...
2008 (English)In: Numerical computation of turbulent gas-particle flow in a backward-facing step. Model comparison with experimental data., Milano: ANIMP SERVIZI SRL , 2008, 63-70 p.Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Milano: ANIMP SERVIZI SRL, 2008
Identifiers
urn:nbn:se:kth:diva-12128 (URN)88-88198-13-X (ISBN)
Conference
11th International Conference on Multiphase Flows In Industrial Plants
Note
QC20100726Available from: 2010-03-08 Created: 2010-03-08 Last updated: 2010-07-26Bibliographically approved
5. Modelling of particle fluctuations in turbulence by stochastic processes
Open this publication in new window or tab >>Modelling of particle fluctuations in turbulence by stochastic processes
(English)Manuscript (Other academic)
Identifiers
urn:nbn:se:kth:diva-7989 (URN)
Note
QC 20100726Available from: 2008-02-20 Created: 2008-02-20 Last updated: 2010-11-24Bibliographically approved

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Citation style
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Output format
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