Some aspects of presumed filtered density functions formulation in the context of large eddy simulation of turbulent reacting flows

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

In Large Eddy Simulations (LES) of turbulent flows, spatially-averaged versions of the Navier-Stokes equations are solved on a grid, which is coarse relative to the smallest turbulent length scales. In order to couple the detailed chemistry and the computed flow field in LES of reacting flows, the so-called filtered density function-based approach for subfilter-scale modelling was suggested. This approach was named as the laminar flamelet and allowed to link the complex chemistry to a single variable, i.e. mixture fraction. The mixture fraction is obtained by the solution of corresponding filtered transport equation and subgrid-scale (SGS) variance (the residual field) is usually modelled. The objective of this article is to present in-depth analysis of filtered density functions (FDFs) by analysing experimental data obtained from two-dimensional planar, laser induced fluorescence measurements in isothermal swirling coaxial turbulent jets at a constant Reynolds number of 29000. The FDFs were analysed as a function of flow swirl number, spatial locations in the flow and were linked to the measured subgrid scale variance. In addition, presumed FDFs were also analysed and associated laminar flamelet solution integration errors were evaluated. It was experimentally found that the FDFs can become unimodal when SGS variance reaches a certain value. However, bimodal FDFs were observed in flow regions with high SGS variance. It was demonstrated that bimodality does not automatically result in large errors in resolved variables when top-hat FDF or -FDF formulations are used. It was suggested that possible source of errors in resolved variables could be linked to the SGS variance models rather than to the presumed FDF-based models.
Original languageEnglish
Title of host publicationProceedings of the 16th International Heat Transfer Conference, IHTC-16
DOIs
Publication statusPublished - 2019
Event16th International Heat Transfer Conference - China National Convention Center, Beijing, China
Duration: 10 Aug 201815 Aug 2018
https://www.ihtc16.org/ (Link to Conference Website)

Conference

Conference16th International Heat Transfer Conference
Abbreviated titleIHTC-16
CountryChina
CityBeijing
Period10/08/1815/08/18
Internet address

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large eddy simulation
turbulent flow
laser induced fluorescence
Navier-Stokes equations
Reynolds number
flow field

Cite this

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title = "Some aspects of presumed filtered density functions formulation in the context of large eddy simulation of turbulent reacting flows",
abstract = "In Large Eddy Simulations (LES) of turbulent flows, spatially-averaged versions of the Navier-Stokes equations are solved on a grid, which is coarse relative to the smallest turbulent length scales. In order to couple the detailed chemistry and the computed flow field in LES of reacting flows, the so-called filtered density function-based approach for subfilter-scale modelling was suggested. This approach was named as the laminar flamelet and allowed to link the complex chemistry to a single variable, i.e. mixture fraction. The mixture fraction is obtained by the solution of corresponding filtered transport equation and subgrid-scale (SGS) variance (the residual field) is usually modelled. The objective of this article is to present in-depth analysis of filtered density functions (FDFs) by analysing experimental data obtained from two-dimensional planar, laser induced fluorescence measurements in isothermal swirling coaxial turbulent jets at a constant Reynolds number of 29000. The FDFs were analysed as a function of flow swirl number, spatial locations in the flow and were linked to the measured subgrid scale variance. In addition, presumed FDFs were also analysed and associated laminar flamelet solution integration errors were evaluated. It was experimentally found that the FDFs can become unimodal when SGS variance reaches a certain value. However, bimodal FDFs were observed in flow regions with high SGS variance. It was demonstrated that bimodality does not automatically result in large errors in resolved variables when top-hat FDF or -FDF formulations are used. It was suggested that possible source of errors in resolved variables could be linked to the SGS variance models rather than to the presumed FDF-based models.",
keywords = "LES, LIF, Measurements, Presumed filtered functions, Reacting flows",
author = "Viacheslav Stetsyuk and Krzysztof Kubiak and Lande Liu and John Chai",
year = "2019",
doi = "10.1615/IHTC16.cms.023612",
language = "English",
booktitle = "Proceedings of the 16th International Heat Transfer Conference, IHTC-16",

}

Stetsyuk, V, Kubiak, K, Liu, L & Chai, J 2019, Some aspects of presumed filtered density functions formulation in the context of large eddy simulation of turbulent reacting flows. in Proceedings of the 16th International Heat Transfer Conference, IHTC-16. 16th International Heat Transfer Conference, Beijing, China, 10/08/18. https://doi.org/10.1615/IHTC16.cms.023612

Some aspects of presumed filtered density functions formulation in the context of large eddy simulation of turbulent reacting flows. / Stetsyuk, Viacheslav; Kubiak, Krzysztof; Liu, Lande; Chai, John.

Proceedings of the 16th International Heat Transfer Conference, IHTC-16. 2019.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

TY - GEN

T1 - Some aspects of presumed filtered density functions formulation in the context of large eddy simulation of turbulent reacting flows

AU - Stetsyuk, Viacheslav

AU - Kubiak, Krzysztof

AU - Liu, Lande

AU - Chai, John

PY - 2019

Y1 - 2019

N2 - In Large Eddy Simulations (LES) of turbulent flows, spatially-averaged versions of the Navier-Stokes equations are solved on a grid, which is coarse relative to the smallest turbulent length scales. In order to couple the detailed chemistry and the computed flow field in LES of reacting flows, the so-called filtered density function-based approach for subfilter-scale modelling was suggested. This approach was named as the laminar flamelet and allowed to link the complex chemistry to a single variable, i.e. mixture fraction. The mixture fraction is obtained by the solution of corresponding filtered transport equation and subgrid-scale (SGS) variance (the residual field) is usually modelled. The objective of this article is to present in-depth analysis of filtered density functions (FDFs) by analysing experimental data obtained from two-dimensional planar, laser induced fluorescence measurements in isothermal swirling coaxial turbulent jets at a constant Reynolds number of 29000. The FDFs were analysed as a function of flow swirl number, spatial locations in the flow and were linked to the measured subgrid scale variance. In addition, presumed FDFs were also analysed and associated laminar flamelet solution integration errors were evaluated. It was experimentally found that the FDFs can become unimodal when SGS variance reaches a certain value. However, bimodal FDFs were observed in flow regions with high SGS variance. It was demonstrated that bimodality does not automatically result in large errors in resolved variables when top-hat FDF or -FDF formulations are used. It was suggested that possible source of errors in resolved variables could be linked to the SGS variance models rather than to the presumed FDF-based models.

AB - In Large Eddy Simulations (LES) of turbulent flows, spatially-averaged versions of the Navier-Stokes equations are solved on a grid, which is coarse relative to the smallest turbulent length scales. In order to couple the detailed chemistry and the computed flow field in LES of reacting flows, the so-called filtered density function-based approach for subfilter-scale modelling was suggested. This approach was named as the laminar flamelet and allowed to link the complex chemistry to a single variable, i.e. mixture fraction. The mixture fraction is obtained by the solution of corresponding filtered transport equation and subgrid-scale (SGS) variance (the residual field) is usually modelled. The objective of this article is to present in-depth analysis of filtered density functions (FDFs) by analysing experimental data obtained from two-dimensional planar, laser induced fluorescence measurements in isothermal swirling coaxial turbulent jets at a constant Reynolds number of 29000. The FDFs were analysed as a function of flow swirl number, spatial locations in the flow and were linked to the measured subgrid scale variance. In addition, presumed FDFs were also analysed and associated laminar flamelet solution integration errors were evaluated. It was experimentally found that the FDFs can become unimodal when SGS variance reaches a certain value. However, bimodal FDFs were observed in flow regions with high SGS variance. It was demonstrated that bimodality does not automatically result in large errors in resolved variables when top-hat FDF or -FDF formulations are used. It was suggested that possible source of errors in resolved variables could be linked to the SGS variance models rather than to the presumed FDF-based models.

KW - LES

KW - LIF

KW - Measurements

KW - Presumed filtered functions

KW - Reacting flows

U2 - 10.1615/IHTC16.cms.023612

DO - 10.1615/IHTC16.cms.023612

M3 - Conference contribution

BT - Proceedings of the 16th International Heat Transfer Conference, IHTC-16

ER -