Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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
Improving LES with OpenFOAM by minimizing numerical dissipation and use of Explicit Algebraic SGS stress model
KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.ORCID iD: 0000-0002-9645-5880
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KTH, Superseded Departments (pre-2005), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.ORCID iD: 0000-0001-8692-0956
KTH, Superseded Departments (pre-2005), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.ORCID iD: 0000-0002-2711-4687
Show others and affiliations
(English)In: Article in journal (Refereed) Submitted
Abstract [en]

There is a rapidly growing interest in using general-purpose CFD codes based on second order finite volume methods for Large-Eddy Simulation (LES) in a wide range of applications,and in many cases involving wall-bounded flows. However, such codes are strongly affected by numerical dissipation and the accuracy obtained for typical LES-resolutions is often poor. In the present study we approach the problem of improving LES capability of such codes by reduction of the numerical dissipation and use of an anisotropy-capturing sub-grid scale (SGS) stress model. The latter is of special importance for wall-resolved LES with resolutions where the SGS anisotropy can be substantial. Here we use the Explicit Algebraic (EA) SGS model (L. Marstorp, et al., J. Fluid Mech. {\bf 639}, (2009)), and comparisons are made for channel flow at friction Reynolds numbers up to 934 with the dynamic Smagorinsky model.The numerical dissipation is reduced byusing an OpenFOAM based custom-built flow solver that modifies the  Rhie \& Chow interpolation and allows to control and minimize its effects without causing numerical instability (in viscous, fully turbulent flows). Different resolutions were used and large improvements of the LES accuracy were demonstrated for skin friction, mean velocity and other flow statistics by use of the new solver in combination with the EA SGS model.By reducing the numerical dissipation and using the EA SGS model the resolution requirements for wall-resolved LES can be significantly reduced.

Keywords [en]
wall-bounded flows, OpenFOAM, SGS modelling
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-264013OAI: oai:DiVA.org:kth-264013DiVA, id: diva2:1371680
Funder
Swedish Research Council, 621-2014- 5700
Note

QC 20191129

Available from: 2019-11-20 Created: 2019-11-20 Last updated: 2019-11-29Bibliographically approved
In thesis
1. Numerical and modelling aspects of large-eddy and hybrid simulations of turbulent flows
Open this publication in new window or tab >>Numerical and modelling aspects of large-eddy and hybrid simulations of turbulent flows
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this study, the explicit algebraic sub-grid scale (SGS) model (EAM) has been extensively validated in wall-resolved large-eddy simulations (LES) of wall-bounded turbulent flows at different Reynolds numbers and a wide range of resolutions. Compared to eddy-viscosity based models, the formulation of the EAM is more consistent with the physics and allows to accurately capture SGS anisotropy,which is relevant especially close to walls.The present work aims to extend the validation of the EAM to larger Reynolds numbers using codes with different orders of numerical accuracy.The first simulations, performed by using a pseudo-spectral code, show that the use of the EAM, compared to the dynamic Smagorinsky model (DSM), leads to significant improvements in the prediction of the first-and second order statistics of turbulent channel flow.These improvements are observed from relatively low to  reasonably high Reynolds numbers and with coarse grids.The evaluation of the EAM was continued by implementing and testing of the EAM in the general-purpose finite-volume code OpenFOAM.Several tests of LES of turbulent channel flow have shown thatthe use of the Rhie and Chow (R&C) interpolation in OpenFOAM induces significant numerical dissipation.A new custom-built solver has been utilized in order to minimize the dissipation without generating significant adverse effects. The use of the EAM, together with the new solver, gives a substantially improved prediction of the mean velocity profiles as compared to predictions using the DSM, resulting in roughly 50% reduction in the grid point requirements to achieve a given degree of accuracy. In periodic hill flow, LES with the EAM agreed reasonably well with the reference dataat different bulk Reynolds numbers and reduced the misprediction of the first- and second order statistics observed in LES with DSM.The reduction of the R&C filter dissipation was also shown to be beneficial for the prediction of the mean quantities. An analysis of the skin friction along the lower wall reveals spanwise-elongated, almost axi-symmetric vortical structures generated by the Kelvin-Helmholtz instability. The structures introduced a significant amount of anisotropy.The last part of the study involved the development of a novel hybrid RANS-LES model where explicit algebraic Reynolds stress modelling is applied in both RANS and LES regions.Validations have been conducted on turbulent channel and periodic hill flows at different Reynolds numbers.The explicit algebraic Reynolds stress model for improved-delayed-detached-eddy simulation (EARSM-IDDES) gives reasonable predictions of the mean quantities and Reynolds stresses in both the geometries considered.The use of EARSM-IDDES, compared to the k-omega SST-IDDES model, improves the estimation of the quantities close to the wall.The present work has proven that the use of EAM in wall-resolved LES of wall-bounded flows in simple and complex geometries leads to a substantial reduction of  computational requirements both in high-accuracy and general-purpose codes, compared to the use of eddy-viscosity models.In hybrid simulations the EARSM-IDDES shows a clear potential in capturing the physics of wall-bounded flows.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. 60
Series
TRITA-SCI-FOU ; 2019:48
Keywords
turbulence, wall-bounded flows, large-eddy simulation, SGS modelling, OpenFOAM, hybrid RANS-LES
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-264025 (URN)978-91-7873-369-9 (ISBN)
Public defence
2019-12-19, F3, Lindstedtsvägen 26, Stockholm, 10:15 (English)
Opponent
Supervisors
Funder
Swedish Research Council, 621-2014- 5700Vinnova, 2017-04887
Note

QC 20191122

Available from: 2019-11-22 Created: 2019-11-20 Last updated: 2019-11-22Bibliographically approved

Open Access in DiVA

No full text in DiVA

Authority records BETA

Brethouwer, GertWallin, StefanJohansson, Arne V.

Search in DiVA

By author/editor
Montecchia, MatteoBrethouwer, GertWallin, StefanJohansson, Arne V.
By organisation
MechanicsLinné Flow Center, FLOWMechanics
Fluid Mechanics and Acoustics

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 48 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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