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Large eddy simulation of channel flow with andwithout periodic constrictions using the explicit algebraic subgrid-scale model
KTH, School of Engineering Sciences (SCI), Mechanics, Turbulence.ORCID iD: 0000-0002-3173-7502
KTH, School of Engineering Sciences (SCI), Mechanics, Turbulence.ORCID iD: 0000-0001-8692-0956
KTH, School of Engineering Sciences (SCI), Mechanics, Turbulence.ORCID iD: 0000-0002-9819-2906
KTH, School of Engineering Sciences (SCI), Mechanics, Turbulence.ORCID iD: 0000-0002-2711-4687
(English)In: Journal of turbulence, ISSN 1468-5248, E-ISSN 1468-5248Article in journal (Other academic) Submitted
Abstract [en]

We analyse the performance of the explicit algebraic subgrid-scale stress model(EASSM) of Marstorp et al. (J. Fluid Mech., vol. 639, 2009, pp. 403–432) inlarge eddy simulation (LES) of plane channel and the flow in a channel withstreamwise periodic hill-shaped constrictions (periodic hill flow) which induceseparation. The LESs are performed with Code Saturne which is an unstructuredcollocated finite volume solver with a second-order spatial discretisationsuitable for LES of incompressible flow in complex geometries. At first, performanceof the EASSM in LES of plane channel flow at two different resolutionsusing the Code Saturne and a pseudo-spectral method is analyzed. It is observedthat EASSM predictions of the mean velocity and Reynolds stresses aremore accurate than with the conventional dynamic Smagorinsky model (DSM).The results with the pseudo-spectral method were in general more accurate.In the second step, LES with the EASSM of flow separation in the periodichill flow is compared to LES with the DSM, no subgrid-scale model and thehighly resolved LES data of Breuer et al. (Computers & Fluids, vol. 38, 2009,pp. 433–457) using the DSM. Results show that the mean velocity profiles,the friction and pressure coefficients, the length and shape of the recirculationbubble, as well as the Reynolds stresses are considerably better predicted bythe EASSM than the DSM and the no subgrid-scale model simulations. It wasalso observed that in some parts of the domain the resolved strain-rate andsubgrid-scale shear stress have the same sign. The DSM cannot produce acorrect subgrid-scale stress in this case, in contrast to the EASSM.

National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-142398OAI: oai:DiVA.org:kth-142398DiVA: diva2:700102
Funder
Swedish Research Council, 621-2010- 6965
Note

QS 2014

Available from: 2014-03-03 Created: 2014-03-03 Last updated: 2017-12-05Bibliographically approved
In thesis
1. 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

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Rasam, AminWallin, StefanBrethouwet, GeertJohansson, Arne

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