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Hybrid URANS/LES turbulence simulation of vortex shedding behind a triangular flameholder

Hasse, C. and Sohm, V. and Wetzel, M. and Durst, B. (2009):
Hybrid URANS/LES turbulence simulation of vortex shedding behind a triangular flameholder.
In: Flow, Turbulence and Combustion, pp. 1-20, 83, (1), DOI: 10.1007/s10494-008-9186-7, [Online-Edition: https://doi.org/10.1007/s10494-008-9186-7],
[Article]

Abstract

In this study a detached eddy simulation (DES) model, which belongs to the group of hybrid URANS/LES turbulence models, is used for the simulation of vortex shedding behind a triangular obstacle. In the near wall region or in regions where the grid resolution is not sufficiently fine to resolve smaller structures, the two-equation RANS shear-stress transport (SST) model is used. In the other regions with higher grid resolution a LES model, which uses a transport equation for the turbulent subgrid energy, is applied. The DES model is first investigated for two standard test cases, namely decaying homogeneous isotropic turbulence and the backward facing step, respectively. For the decaying homogeneous isotropic turbulence test case the evolution of the energy spectra in wavenumber space for different times are studied for both the DES and a Smagorinsky type LES model. Different grid resolutions are analyzed with a special emphasis on the modeling constant connecting the filter length scale to the grid size. The results are compared to experimental data. The backward facing step test case is used to study the model behavior for a case with a transition region between a RANS modeling approach close to the wall and LES based modeling in the intense shear flow region. The final application is the simulation of the vortex shedding behind a triangular obstacle. First, the influence of the inlet condition formulation is studied in detail as they can have a significant influence especially for LES based models. Detailed comparisons between simulation and experiment for the flow structure past the obstacle and statistical quantities such as the shedding frequency are shown. Finally the additional temporal and spatial information provided by the DES model is used to show the predicted anisotropy of turbulence. 2008 Springer Science+Business Media B.V.

Item Type: Article
Erschienen: 2009
Creators: Hasse, C. and Sohm, V. and Wetzel, M. and Durst, B.
Title: Hybrid URANS/LES turbulence simulation of vortex shedding behind a triangular flameholder
Language: German
Abstract:

In this study a detached eddy simulation (DES) model, which belongs to the group of hybrid URANS/LES turbulence models, is used for the simulation of vortex shedding behind a triangular obstacle. In the near wall region or in regions where the grid resolution is not sufficiently fine to resolve smaller structures, the two-equation RANS shear-stress transport (SST) model is used. In the other regions with higher grid resolution a LES model, which uses a transport equation for the turbulent subgrid energy, is applied. The DES model is first investigated for two standard test cases, namely decaying homogeneous isotropic turbulence and the backward facing step, respectively. For the decaying homogeneous isotropic turbulence test case the evolution of the energy spectra in wavenumber space for different times are studied for both the DES and a Smagorinsky type LES model. Different grid resolutions are analyzed with a special emphasis on the modeling constant connecting the filter length scale to the grid size. The results are compared to experimental data. The backward facing step test case is used to study the model behavior for a case with a transition region between a RANS modeling approach close to the wall and LES based modeling in the intense shear flow region. The final application is the simulation of the vortex shedding behind a triangular obstacle. First, the influence of the inlet condition formulation is studied in detail as they can have a significant influence especially for LES based models. Detailed comparisons between simulation and experiment for the flow structure past the obstacle and statistical quantities such as the shedding frequency are shown. Finally the additional temporal and spatial information provided by the DES model is used to show the predicted anisotropy of turbulence. 2008 Springer Science+Business Media B.V.

Journal or Publication Title: Flow, Turbulence and Combustion
Volume: 83
Number: 1
Uncontrolled Keywords: Backward-facing step; Detached eddy simulations; Energy spectra; Experimental data; Filter length; Flameholder; Flow regions; Grid resolution; Grid size; Homogeneous isotropic turbulence; Hybrid URANS/LES; Inlet conditions; Near-wall region; RANS modeling; Shear-stress transport; Shedding frequencies; Spatial informations; SST DES; Standard tests; Statistical quantity; Sub-grid; Test case; Transition regions; Transport equation; Turbulence simulation; Two-equation; Wavenumber spaces, Atmospheric temperature; Channel flow; Facings; Flow simulation; Large eddy simulation; Model structures; Navier Stokes equations; Simulators; Submarine geophysics; Turbulence; Turbulent flow; Vortex shedding, Turbulence models
Divisions: 16 Department of Mechanical Engineering > Simulation of reactive Thermo-Fluid Systems (STFS)
16 Department of Mechanical Engineering
Date Deposited: 29 Nov 2017 09:44
DOI: 10.1007/s10494-008-9186-7
Official URL: https://doi.org/10.1007/s10494-008-9186-7
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