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Simulations of turbulent boundary layers with heat transfer
KTH, School of Engineering Sciences (SCI), Mechanics.
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH , 2009. , vii, 36 p.
Series
Trita-MEK, ISSN 0348-467X ; 2009:14
Keyword [en]
DNS, LES, Turbulent boundary layer, passive scalar, large-scale structures, massively parallel simulations
Identifiers
URN: urn:nbn:se:kth:diva-11320ISBN: 978-91-7415-443-6 (print)OAI: oai:DiVA.org:kth-11320DiVA: diva2:273694
Presentation
2009-10-22, Sal E3, OB 14, Stockholm, Sweden, 15:15 (English)
Opponent
Supervisors
Available from: 2009-10-26 Created: 2009-10-23 Last updated: 2010-10-26Bibliographically approved
List of papers
1. Spectral simulations of wall-bounded flows on massively-parallel computers
Open this publication in new window or tab >>Spectral simulations of wall-bounded flows on massively-parallel computers
2008 (English)Report (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH, 2008
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-25549 (URN)
Note

QC 20101026

Available from: 2010-10-26 Created: 2010-10-26 Last updated: 2014-05-23Bibliographically approved
2. Turbulent boundary layers up to Re-theta=2500 studied through simulation and experiment
Open this publication in new window or tab >>Turbulent boundary layers up to Re-theta=2500 studied through simulation and experiment
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2009 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Physics of Fluids, Vol. 21, no 5, 051702- p.Article in journal (Refereed) Published
Abstract [en]

Direct numerical simulations (DNSs) and experiments of a spatially developing zero-pressure-gradient turbulent boundary layer are presented up to Reynolds number Re-theta=2500, based on momentum thickness theta and free-stream velocity. For the first time direct comparisons of DNS and experiments of turbulent boundary layers at the same (computationally high and experimentally low) Re-theta are given, showing excellent agreement in skin friction, mean velocity, and turbulent fluctuations. These results allow for a substantial reduction of the uncertainty of boundary-layer data, and cross validate the numerical setup and experimental technique. The additional insight into the flow provided by DNS clearly shows large-scale turbulent structures, which scale in outer units growing with Re-theta, spanning the whole boundary-layer height.

Keyword
boundary layer turbulence, flow simulation, wall-shear-stress, region, flows
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-18466 (URN)10.1063/1.3139294 (DOI)000266500500002 ()2-s2.0-66849124872 (Scopus ID)
Note

QC 20150721

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
3. High-Reynolds number turbulent boundary layers studied by numerical simulation
Open this publication in new window or tab >>High-Reynolds number turbulent boundary layers studied by numerical simulation
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2009 (English)In: Bulletin of the American Physical Society, APS Physics , 2009Conference paper, Published paper (Refereed)
Abstract [en]

Direct and large-eddy simulations (DNS and LES) of spatially developing high-Reynolds number turbulent boundary layers (Reθ up to 4300) under zero pressure gradient are studied. The inflow of the computational domain and the tripping of the boundary layer is located at low Reynolds numbers Reθ 350, a position where natural transition to turbulence can be expected. The simulation thus includes the spatial evolution of the boundary layer for an extended region, providing statistics and budget terms at each streamwise position. The data is obtained with up to O(10^10) grid points using a parallelised, fully spectral method. The DNS and LES results are critically evaluated and validated, in comparison with other relevant data, e.g. the experiments by "Osterlund et al. (1999). Quantities difficult or even impossible to measure, e.g. pressure fluctuations and complete Reynolds stress budgets, shall be discussed. In addition, special emphasis is put on a further quantification of the large-scale structures appearing in the flow, and their relation to other wall-bounded flow as e.g. channel flow. The results clearly show that with today's computer power Reynolds numbers relevant for industrial applications can be within reach for DNS/LES.

Place, publisher, year, edition, pages
APS Physics, 2009
Series
Bulletin of the American Physical Society, ISSN 0003-0503 ; 19
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-25548 (URN)
Conference
American Physical Society, 62nd Annual Meeting of the APS Division of Fluid Dynamics, November 22-24, 2009, Minneapolis, Minnesota
Note
QC 20101026Available from: 2010-10-26 Created: 2010-10-26 Last updated: 2010-10-26Bibliographically approved
4. DNS of a spatially developing turbulent boundary layer with passive scalar transport
Open this publication in new window or tab >>DNS of a spatially developing turbulent boundary layer with passive scalar transport
2009 (English)In: International Journal of Heat and Fluid Flow, ISSN 0142-727X, E-ISSN 1879-2278, Vol. 30, no 5, 916-929 p.Article in journal (Refereed) Published
Abstract [en]

A direct numerical simulation (DNS) of a spatially developing turbulent boundary layer over a flat plate under zero pressure gradient (ZPG) has been carried out. The evolution of several passive scalars with both isoscalar and isoflux wall boundary condition are computed during the simulation. The Navier-Stokes equations as well as the scalar transport equation are solved using a fully spectral method. The highest Reynolds number based on the free-stream velocity U-infinity and momentum thickness 0 is Re-0 = 830, and the molecular Prandtl numbers are 0.2, 0.71 and 2. To the authors' knowledge, this Reynolds number is to date the highest with such a variety of scalars. A large number of turbulence statistics for both flow and scalar fields are obtained and compared when possible to existing experimental and numerical simulations at comparable Reynolds number. The main focus of the present paper is on the statistical behaviour of the scalars in the outer region of the boundary layer, distinctly different from the channel-flow simulations. Agreements as well as discrepancies are discussed while the influence of the molecular Prandtl number and wall boundary conditions is also highlighted. A Pr scaling for various quantities is proposed in outer scalings. In addition, spanwise two-point correlation and instantaneous fields are employed to investigate the near-wall streak spacing and the coherence between the velocity and the scalar fields. Probability density functions (PDF) and joint probability density functions (JPDF) are shown to identify the intermittency both near the wall and in the outer region of the boundary layer. The present simulation data will be available online for the research community.

Keyword
Turbulent boundary layer, Passive scalar, Direct numerical simulation, (DNS), Prandtl number, direct numerical-simulation, low-reynolds-number, near-wall region, channel flow, heat-transfer, prandtl number, temperature-fluctuations, velocity, respect
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-18923 (URN)10.1016/j.ijheatfluidflow.2009.06.007 (DOI)000271355100012 ()2-s2.0-70249119222 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
5. Simulations of heat transfer in a boundary layer subject to free-stream turbulence
Open this publication in new window or tab >>Simulations of heat transfer in a boundary layer subject to free-stream turbulence
2010 (English)In: Journal of turbulence, ISSN 1468-5248, E-ISSN 1468-5248, Vol. 11, no 45, 1-33 p.Article in journal (Refereed) Published
Abstract [en]

The present study investigates the effects of ambient free-stream turbulence (FST) on the momentum and heat transfer in a spatially developing, turbulent flat-plate boundary layer via large-eddy simulations using the ADM-RT model. Due to a local turbulence intensity Tu of 7% in the free stream, the skin-friction coefficient cf and Stanton number St are substantially elevated up to 25% and 32%, respectively, in the fully turbulent region (Reτ=300). This observation is in qualitative agreement with earlier experimental studies. Moreover, the Reynolds analogy factor is found to increase with the FST intensity Tu. The depression of both mean velocity and temperature profiles in the wake region due to FST is observed. In addition, the pre-multiplied spanwise spectra show that the outer peak residing in the logarithmic region in the case without FST is replaced by a new peak located near the boundary layer edge with a spanwise scale of about 3-4δ95. It is suggested that these large-scale events and their imprint throughout the boundary layer cause the elevation of both the skin friction and heat transfer on the solid surface.

Keyword
free-stream turbulence (FST), large-eddy simulation (LES), heat transfer, turbulent boundary layer
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-25546 (URN)10.1080/14685248.2010.521505 (DOI)000283368600001 ()
Note
QC 20101026Available from: 2010-10-26 Created: 2010-10-26 Last updated: 2017-12-12Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
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