Title 
Numerical investigation of electroconvection induced by strong unipolar injection between two rotating coaxial cylinders 
Authors 
Traore, Philippe , Wu, Jian , Louste, Christophe , DURAN OLIVENCIA, FRANCISCO JOSÉ, Vazquez, Pedro A. , Perez, Alberto T. 
External publication 
Si 
Means 
J. Electrost. 
Scope 
Article 
Nature 
Científica 
JCR Quartile 
3 
SJR Quartile 
2 
JCR Impact 
1.68800 
Publication date 
01/08/2018 
ISI 
000441490100009 
DOI 
10.1016/j.elstat.2018.06.003 
Abstract 
In this paper, the interaction between a Couette shear flow and an electroconvective motion induced by an unipolar injection between twocoaxial cylinders is numerically investigated. A flow is generated by two counterrotating coaxial cylinders inducing a shear flow. Space charges are injected in the flow through a metallic electrode placed on the inner cylinder and brought to a given potential. Transient numerical simulations have been carried out to investigate the structure of the induced flow. The entire set of the coupled NavierStokes and EHD equations is solved using an efficient finite volume technique. The behaviour of the flow subjected to an applied voltage between the two electrodes is analyzed and time evolution of the charge density distributions is presented. The interaction between the convective motion induced by space charge injection and the mainstream flow, emphasizes the appearance of periodic counterrotating electroconvective cells. The electroconvective cells are convected in the annular space by the azimuthal fluid velocity. From the stability point of view the bifurcation diagram is very similar to the one obtained in the case when Re = 0. We observe a threshold value Tc of the instability parameters T above which the electroconvective instability initiates. A nonlinear criterion Tf under which the electroconvective motion is suppressed is also found. When increasing the Reynolds number the flow induced by the two rotating cylinders has a sweeping effect on the charge density distribution. Consequently the instability parameter T must be drastically increased to allow the electroconvective instability to develop. For Re = 10 a subcritical instability characterized by an hysteresis loop and therefore a linear and nonlinear criteria, Tc and Tf respectively, are determined. While for Re = 0, Tc = 122.42 and Tf = 86.5, for Re = 10 we numerically found that Tc = 802 and Tf = 722. The magnitude of the linear and nonlinear criteria are directly linked to the value of the Reynolds number. 
Keywords 
Electrohydrodynamics; Couette shear flow; Numerical analysis; Dielectric liquid; Charge injection; Nnular electroconvection 
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