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Characteristics of electrohydrodynamic roll structures in laminar planar Couette flow

Characteristics of electrohydrodynamic roll structures in laminar planar Couette flow
Characteristics of electrohydrodynamic roll structures in laminar planar Couette flow
The behaviour of an incompressible dielectric liquid subjected to a laminar planar Couette flow with unipolar charge injection is investigated numerically in two dimensions. The computations show new morphological characteristics of roll structures that arise in this forced electro-convection problem. The charge and velocity magnitude distributions between the two parallel electrodes are discussed as a function of the top wall velocity and the EHD Rayleigh number, T for the case of strong charge injection. A wide enough parametric space is investigated such that the observed EHD roll structures progress through three regimes. These regimes are defined by the presence of a single or double-roll free convective structure as observed elsewhere (Vazquez et al 2008 J. Phys. D 41 175303), a sheared or stretched roll structure, and finally by a regime where the perpendicular velocity gradient is sufficient to prevent the generation of a roll. These three regimes have been delineated as a function of the wall to ionic drift velocity Uw/kE, and the T number. In the stretched regime, an increase in Uw/kE can reduce charge and momentum fluctuations whilst in parallel de-stratify charge in the region between the two electrodes. The stretched roll regime is also characterised by a substantial influence of Uw/kE on the steady development time, however in the traditional non-stretched roll structure regime, no influence of Uw/kE on the development time is noted.
electrohydrodynamics, couette flow, charge injection
0022-3727
1-13
Shrimpton, J.
9cf82d2e-2f00-4ddf-bd19-9aff443784af
Kourmatzis, A.
7f5776c2-eadb-41a8-bef3-79a1ebb1933f
Shrimpton, J.
9cf82d2e-2f00-4ddf-bd19-9aff443784af
Kourmatzis, A.
7f5776c2-eadb-41a8-bef3-79a1ebb1933f

Shrimpton, J. and Kourmatzis, A. (2016) Characteristics of electrohydrodynamic roll structures in laminar planar Couette flow. Journal of Physics D: Applied Physics, 49 (4), 1-13. (doi:10.1088/0022-3727/49/4/045503).

Record type: Article

Abstract

The behaviour of an incompressible dielectric liquid subjected to a laminar planar Couette flow with unipolar charge injection is investigated numerically in two dimensions. The computations show new morphological characteristics of roll structures that arise in this forced electro-convection problem. The charge and velocity magnitude distributions between the two parallel electrodes are discussed as a function of the top wall velocity and the EHD Rayleigh number, T for the case of strong charge injection. A wide enough parametric space is investigated such that the observed EHD roll structures progress through three regimes. These regimes are defined by the presence of a single or double-roll free convective structure as observed elsewhere (Vazquez et al 2008 J. Phys. D 41 175303), a sheared or stretched roll structure, and finally by a regime where the perpendicular velocity gradient is sufficient to prevent the generation of a roll. These three regimes have been delineated as a function of the wall to ionic drift velocity Uw/kE, and the T number. In the stretched regime, an increase in Uw/kE can reduce charge and momentum fluctuations whilst in parallel de-stratify charge in the region between the two electrodes. The stretched roll regime is also characterised by a substantial influence of Uw/kE on the steady development time, however in the traditional non-stretched roll structure regime, no influence of Uw/kE on the development time is noted.

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Accepted/In Press date: 25 November 2015
e-pub ahead of print date: 24 December 2015
Published date: 3 February 2016
Keywords: electrohydrodynamics, couette flow, charge injection
Organisations: Aeronautics, Astronautics & Comp. Eng

Identifiers

Local EPrints ID: 384863
URI: https://eprints.soton.ac.uk/id/eprint/384863
ISSN: 0022-3727
PURE UUID: 2b3a1735-2673-4f90-ba79-7f24673e517e

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Date deposited: 11 Jan 2016 16:52
Last modified: 19 Jul 2019 20:24

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