Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Effects of modelling, resolution and anisotropy of subgrid-scales on large eddy simulations of channel flow
KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics, Turbulence.ORCID iD: 0000-0002-3173-7502
KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics, Turbulence.ORCID iD: 0000-0002-9819-2906
KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics.ORCID iD: 0000-0001-9627-5903
KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics.
Show others and affiliations
2011 (English)In: Journal of turbulence, ISSN 1468-5248, E-ISSN 1468-5248, Vol. 12, no 10, 1-20 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, the effect of subgrid-scale (SGS) modelling, grid resolution and anisotropy of the subgrid-scales on large eddy simulation (LES) is investigated. LES of turbulent channel flow is performed at Re=934, based on friction velocity and channel half width, for a wide range of resolutions. The dynamic Smagorinsky model (DS), the high-pass filtered dynamic Smagorinsky model (HPF) based on the variational multiscale method and the recent explicit algebraic model (EA), which accounts for the anisotropy of the SGS stresses are considered. The first part of the paper is focused on the resolution effects on LES, where the performances of the three SGS models at different resolutions are compared to direct numerical simulation (DNS) results. The results show that LES using eddy viscosity SGS models is very sensitive to resolution. At coarse resolutions, LES with the DS and the HPF models deviate considerably from DNS, whereas LES with the EA model still gives reasonable results. Further analysis shows that the two former models do not accurately predict the SGS dissipation near the wall, while the latter does, even at coarse resolutions. In the second part, the effect of SGS modelling on LES predictions of near-wall and outer-layer turbulent structures is discussed. It is found that different models predict near-wall turbulent structures of different sizes. Analysis of the spectra shows that although near-wall scales are not resolved at coarse resolutions, large-scale motions can be reasonably captured in LES using all the tested models.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2011. Vol. 12, no 10, 1-20 p.
Keyword [en]
large eddy simulation, subgrid-scale modelling, resolution effects, subgrid-scale anisotropy, channel flow
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-31322DOI: 10.1080/14685248.2010.541920ISI: 000287703700001Scopus ID: 2-s2.0-83055170803OAI: oai:DiVA.org:kth-31322DiVA: diva2:404718
Funder
Swedish Research Council, 621-2010-6965Swedish Research Council, 621-2007-4232Swedish e‐Science Research Center
Note

QC 20110318

Available from: 2011-03-18 Created: 2011-03-14 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Explicit algebraic subgrid-scale stress and passive scalar flux modeling in large eddy simulation
Open this publication in new window or tab >>Explicit algebraic subgrid-scale stress and passive scalar flux modeling in large eddy simulation
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The present thesis deals with a number of challenges in the field of large eddy simulation (LES). These include the performance of subgrid-scale (SGS) models at fairly high Reynolds numbers and coarse resolutions, passive scalar and stochastic modeling in LES. The fully-developed turbulent channel flow is used as the test case for these investigations. The advantage of this particular test case is that highly accurate pseudo-spectral methods can be used for the discretization of the governing equations. In the absence of discretization errors, a better understanding of the subgrid-scale model performance can be achieved. Moreover, the turbulent channel flow is a challenging test case for LES, since it shares some of the common important features of all wall-bounded turbulent flows. Most commonly used eddy-viscosity-type models are suitable for moderately to highly-resolved LES cases, where the unresolved scales are approximately isotropic. However, this makes simulations of high Reynolds number wall-bounded flows computationally expensive. In contrast, explicit algebraic (EA) model takes into account the anisotropy of SGS motions and performs well in predicting the flow statistics in coarse-grid LES cases. Therefore, LES of high Reynolds number wall-bounded flows can be performed at much lower number of grid points in comparison with other models. A demonstration of the resolution requirements for the EA model in comparison with the dynamic Smagorinsky and its high-pass filtered version for a fairly high Reynolds number is given in this thesis. One of the shortcomings of the commonly used eddy diffusivity model arises from its assumption of alignment of the SGS scalar flux vector with the resolved scalar gradients. However, better SGS scalar flux models that overcome this issue are very few. Using the same methodology that led to the EA SGS stress model, a new explicit algebraic SGS scalar flux model is developed, which allows the SGS scalar fluxes to be partially independent of the resolved scalar gradient. The model predictions are verified and found to improve the scalar statistics in comparison with the eddy diffusivity model. The intermittent nature of energy transfer between the large and small scales of turbulence is often not fully taken into account in the formulation of SGS models both for velocity and scalar. Using the Langevin stochastic differential equation, the EA models are extended to incorporate random variations in their predictions which lead to a reasonable amount of backscatter of energy from the SGS to the resolved scales. The stochastic EA models improve the predictions of the SGS dissipation by decreasing its length scale and improving the shape of its probability density function.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 30 p.
Series
Trita-MEK, ISSN 0348-467X ; 2011:05
Keyword
Turbulence, Large eddy simulation, explicit algebraic subgrid-scale model, passive scalar, stochastic modeling, backscatter
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-34453 (URN)978-91-7501-016-8 (ISBN)
Presentation
2011-05-30, H1, KTH, Teknikringen 33, Stockholm, 10:15 (English)
Opponent
Supervisors
Funder
Swedish Research Council, 621-2010-6965Swedish e‐Science Research Center
Note
QC 20110615Available from: 2011-06-15 Created: 2011-06-08 Last updated: 2012-05-24Bibliographically approved
2. Anisotropy-resolving subgrid-scale modelling using explicit algebraic closures for large eddy simulation
Open this publication in new window or tab >>Anisotropy-resolving subgrid-scale modelling using explicit algebraic closures for large eddy simulation
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present thesis deals with the development and performance analysis ofanisotropy-resolving models for the small, unresolved scales (”sub-grid scales”,SGS) in large eddy simulation (LES). The models are characterised by a descriptionof anisotropy by use of explicit algebraic models for both the subgridscale(SGS) stress tensor (EASSM) and SGS scalar flux vector (EASSFM). Extensiveanalysis of the performance of the explicit algebraic SGS stress model(EASSM) has been performed and comparisons made with the conventionalisotropic dynamic eddy viscosity model (DEVM). The studies include LES ofplane channel flow at relatively high Reynolds numbers and a wide range ofresolutions and LES of separated flow in a channel with streamwise periodichill-shaped constrictions (periodic hill flow) at coarse resolutions. The formersimulations were carried out with a pseudo-spectral Navier–Stokes solver, whilethe latter simulations were computed with a second-order, finite-volume basedsolver for unstructured grids. The LESs of channel flow demonstrate that theEASSM gives a good description of the SGS anisotropy, which in turn gives ahigh degree of resolution independence, contrary to the behaviour of LES predictionsusing the DEVM. LESs of periodic hill flow showed that the EASSMalso for this case gives significantly better flow predictions than the DEVM.In particular, the reattachment point was much better predicted with the EASSMand reasonably well predicted even at very coarse resolutions, where theDEVM is unable to predict a proper flow separation.The explicit algebraic SGS scalar flux model (EASSFM) is developed toimprove LES predictions of complex anisotropic flows with turbulent heat ormass transfer, and can be described as a nonlinear tensor eddy diffusivity model.It was tested in combination with the EASSM for the SGS stresses, and itsperformance was compared to the conventional dynamic eddy diffusivity model(DEDM) in channel flow with and without system rotation in the wall-normaldirection. EASSM and EASSFM gave predictions of high accuracy for meanvelocity and mean scalar fields, as well as stresses and scalar flux components.An extension of the EASSM and EASSFM, based on stochastic differentialequations of Langevin type, gave further improvements. In contrast to conventionalmodels, these extended models are able to describe intermittent transferof energy from the small, unresolved scales, to the resolved large ones.The present study shows that the EASSM/EASSFM gives a clear improvementof LES of wall-bounded flows in simple, as well as in complex geometriesin comparison with simpler SGS models. This is also shown to hold for a widerange of resolutions and is particularly accentuated for coarse resolution. The advantages are also demonstrated both for high-order numerical schemes andfor solvers using low-order finite volume methods. The models therefore havea clear potential for more applied computational fluid mechanics.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. vii, 48 p.
Series
TRITA-MEK, ISSN 0348-467X ; 2014:07 2014:07
Keyword
Turbulence, large eddy simulation, explicit algebraic subgridscale model, passive scalar, stochastic modelling, periodic hill flow
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-142401 (URN)978-91-7595-038-9 (ISBN)
Public defence
2014-03-14, F3, Lindstedsvägen 26, KTH, Stockholm, 10:15 (English)
Opponent
Supervisors
Projects
Explicit algebraic sub-grid scale modelling for large-eddy simulations
Funder
Swedish Research Council, 621-2010- 6965
Note

QC 20140304

Available from: 2014-03-04 Created: 2014-03-03 Last updated: 2014-03-04Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Authority records BETA

Rasam, AminBrethouwer, GeertSchlatter, PhilippJohansson, Arne V.

Search in DiVA

By author/editor
Rasam, AminBrethouwer, GeertSchlatter, PhilippLi, QiangJohansson, Arne V.
By organisation
Linné Flow Center, FLOWTurbulenceMechanics
In the same journal
Journal of turbulence
Mechanical Engineering

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 64 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf