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Turbulence closure models for free electroconvection

Turbulence closure models for free electroconvection
Turbulence closure models for free electroconvection

Electroconvection has been simulated in a number of recent studies, given its application in heat transfer enhancement, electrostatic atomizers and flow control. In practical applications, such as in charge injection atomizers, the electric Reynolds number can be sufficiently high such that the well-described ordered large scale electrohydrodynamic (EHD) instabilities that normally appear in electroconvection can dissipate and form into a wider distribution of length-scales. This purely electrohydrodynamically driven chaotic flow has features that resemble turbulent natural convection, and can dominate the operational regime of practical devices. Despite its practical relevance, Reynolds averaged turbulence model closures for EHD are unavailable, which currently makes direct numerical simulation the main viable option for EHD flows. Closure of EHD turbulence in free electro-convection is examined here through implementation of Reynolds stress model (RSM) closures using EHD specific timescales for the unclosed terms appearing in the turbulent scalar flux and space-charge scalar variance equations. A new closure for the highly non-linear triple correlation (qEu¯), a term which is specific to EHD, is also presented. The work demonstrates that Reynolds stress closures are a feasible modeling route for EHD flows, with errors approaching similar values as in thermal Rayleigh–Benard convection at analogous levels of turbulence.

Electrohydrodynamics, Free convection, Turbulence closures
0142-727X
153-159
Kourmatzis, A.
2e6a16aa-3a9e-42ae-8e1d-a9b7bf9d637d
Shrimpton, J. S.
9cf82d2e-2f00-4ddf-bd19-9aff443784af
Kourmatzis, A.
2e6a16aa-3a9e-42ae-8e1d-a9b7bf9d637d
Shrimpton, J. S.
9cf82d2e-2f00-4ddf-bd19-9aff443784af

Kourmatzis, A. and Shrimpton, J. S. (2018) Turbulence closure models for free electroconvection. International Journal of Heat and Fluid Flow, 71, 153-159. (doi:10.1016/j.ijheatfluidflow.2018.03.014).

Record type: Article

Abstract

Electroconvection has been simulated in a number of recent studies, given its application in heat transfer enhancement, electrostatic atomizers and flow control. In practical applications, such as in charge injection atomizers, the electric Reynolds number can be sufficiently high such that the well-described ordered large scale electrohydrodynamic (EHD) instabilities that normally appear in electroconvection can dissipate and form into a wider distribution of length-scales. This purely electrohydrodynamically driven chaotic flow has features that resemble turbulent natural convection, and can dominate the operational regime of practical devices. Despite its practical relevance, Reynolds averaged turbulence model closures for EHD are unavailable, which currently makes direct numerical simulation the main viable option for EHD flows. Closure of EHD turbulence in free electro-convection is examined here through implementation of Reynolds stress model (RSM) closures using EHD specific timescales for the unclosed terms appearing in the turbulent scalar flux and space-charge scalar variance equations. A new closure for the highly non-linear triple correlation (qEu¯), a term which is specific to EHD, is also presented. The work demonstrates that Reynolds stress closures are a feasible modeling route for EHD flows, with errors approaching similar values as in thermal Rayleigh–Benard convection at analogous levels of turbulence.

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Accepted/In Press date: 24 March 2018
e-pub ahead of print date: 7 April 2018
Published date: 1 June 2018
Keywords: Electrohydrodynamics, Free convection, Turbulence closures

Identifiers

Local EPrints ID: 420102
URI: http://eprints.soton.ac.uk/id/eprint/420102
ISSN: 0142-727X
PURE UUID: 1e1b4a27-3df6-4a4c-b606-5cc623efdcb9

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Date deposited: 26 Apr 2018 16:30
Last modified: 07 Oct 2020 06:34

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