Direct numerical simulations and spectral proper orthogonal decomposition analysis of shocklet-containing turbulent channel counter-flows
Direct numerical simulations and spectral proper orthogonal decomposition analysis of shocklet-containing turbulent channel counter-flows
Counter-flow configurations in a confined channel flow provide an efficient framework to study high intensity turbulent mixing processes. In a previous study (Physical Review Fluids, 6(9), p.094603), a wall-bounded counter-flow turbulent channel configuration was presented as an effective framework for addressing certain challenges related to the study of compressibility effects on turbulence as an alternative to free shear layer and Poiseuille/Couette type flows. Here, the previous direct numerical simulations are extended to a higher Mach number (M=0.7) to quantify direct and indirect effects of compressibility. It is found that the configuration is able to produce large numbers of embedded shocklets, leading to significant asymmetry in probability density functions of dilatation. Reducing the Prandtl number from 0.7 to 0.2 increases the compressibility effect further by reducing the bulk heating in the channel. A peak turbulent Mach number close to unity is obtained, for which the contribution of the dilatational dissipation to the total dissipation is nevertheless found to be limited to ∼6%. Indirect effects of compressibility are much larger, with changes of up to 40% in Favre normal stresses, despite the mean flow and shear stress being almost unaffected by compressibility in this configuration. Given the inflectional nature of the turbulent mean flow it is also interesting to identify large structures. Spectral Proper Orthogonal Decomposition (SPOD) reveals a full spectrum with a slow decay of energy with mode number. Mode shapes are three-dimensional with the low frequencies displaying elongated streaks in the velocity field at the channel centre plane.
Compressible turbulence, Counter-flow, Direct numerical simulation, Modal analysis, OpenSBLI, SPOD, Shocklet
Hamzehloo, Arash
456b886d-3edb-4dd3-9512-0cb0fb5cf146
Lusher, David
dd681c9e-ceae-409b-8153-8248c13a18e5
Sandham, Neil
0024d8cd-c788-4811-a470-57934fbdcf97
December 2023
Hamzehloo, Arash
456b886d-3edb-4dd3-9512-0cb0fb5cf146
Lusher, David
dd681c9e-ceae-409b-8153-8248c13a18e5
Sandham, Neil
0024d8cd-c788-4811-a470-57934fbdcf97
Hamzehloo, Arash, Lusher, David and Sandham, Neil
(2023)
Direct numerical simulations and spectral proper orthogonal decomposition analysis of shocklet-containing turbulent channel counter-flows.
International Journal of Heat and Fluid Flow, 104, [109229].
(doi:10.1016/j.ijheatfluidflow.2023.109229).
Abstract
Counter-flow configurations in a confined channel flow provide an efficient framework to study high intensity turbulent mixing processes. In a previous study (Physical Review Fluids, 6(9), p.094603), a wall-bounded counter-flow turbulent channel configuration was presented as an effective framework for addressing certain challenges related to the study of compressibility effects on turbulence as an alternative to free shear layer and Poiseuille/Couette type flows. Here, the previous direct numerical simulations are extended to a higher Mach number (M=0.7) to quantify direct and indirect effects of compressibility. It is found that the configuration is able to produce large numbers of embedded shocklets, leading to significant asymmetry in probability density functions of dilatation. Reducing the Prandtl number from 0.7 to 0.2 increases the compressibility effect further by reducing the bulk heating in the channel. A peak turbulent Mach number close to unity is obtained, for which the contribution of the dilatational dissipation to the total dissipation is nevertheless found to be limited to ∼6%. Indirect effects of compressibility are much larger, with changes of up to 40% in Favre normal stresses, despite the mean flow and shear stress being almost unaffected by compressibility in this configuration. Given the inflectional nature of the turbulent mean flow it is also interesting to identify large structures. Spectral Proper Orthogonal Decomposition (SPOD) reveals a full spectrum with a slow decay of energy with mode number. Mode shapes are three-dimensional with the low frequencies displaying elongated streaks in the velocity field at the channel centre plane.
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TSPF12_SI_IJHFF_Revised_2_Clean
- Accepted Manuscript
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1-s2.0-S0142727X23001285-main
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More information
Accepted/In Press date: 4 October 2023
e-pub ahead of print date: 11 October 2023
Published date: December 2023
Additional Information:
Funding Information:
Dr Arash Hamzehloo was funded by the UK Turbulence Consortium (EPSRC grant EP/R029326/1 ). Dr David J Lusher was funded by EPSRC grant EP/L015382/1 . The authors acknowledge the use of the Cambridge Tier-2 system operated by the University of Cambridge Research Computing Service under an EPSRC Tier-2 capital grant ( EP/P020259/1 ). The flow solver OpenSBLI is available at https://opensbli.github.io .
Publisher Copyright:
© 2023 The Author(s)
Keywords:
Compressible turbulence, Counter-flow, Direct numerical simulation, Modal analysis, OpenSBLI, SPOD, Shocklet
Identifiers
Local EPrints ID: 482738
URI: http://eprints.soton.ac.uk/id/eprint/482738
ISSN: 0142-727X
PURE UUID: 009b1a81-d3d3-446d-bdd4-7cd0a99f7d88
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Date deposited: 12 Oct 2023 16:38
Last modified: 18 Mar 2024 03:57
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Author:
Arash Hamzehloo
Author:
David Lusher
Author:
Neil Sandham
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