title: Onset of convection in a finite two-dimensional container due to unipolar injection of ions.
abstract: This work addresses the stability of a two-dimensional plane layer of a dielectric liquid enclosed in wall bounded cavities of different aspect ratios and subjected to unipolar injection of ions. Numerical simulations have been conducted to investigate the effect of lateral walls, especially in the development of the electroconvective instability. It is found that an unexpected change of the bifurcation nature occurs for certain cavity aspect ratios. We show that above the linear stability threshold for the rest state a supercritical bifurcation arises. This bifurcation takes place at a given value T(c1) of the parameter T (the electric Rayleigh number). Then, a second subcritical bifurcation occurs at a second threshold T(c2), featuring a typical hysteresis loop with an associated nonlinear criterion T(f), which is very characteristic of the Coulomb-driven convection. This behavior has been confirmed by different numerical codes based on different numerical methods. The physical mechanism which leads to this situation is analyzed and discussed. The evolution of the bifurcation diagrams with the aspect ratio of the cavity is also provided and analyzed.
authors: Institut PPRIME, Département Fluide-Thermique-Combustion, Boulevard Pierre et Marie Curie, Boîte Postale 30179, 86962 Futuroscope-Chasseneuil, France.
authors: Jian
authors: J
authors: Wu
authors: Institut PPRIME, Département Fluide-Thermique-Combustion, Boulevard Pierre et Marie Curie, Boîte Postale 30179, 86962 Futuroscope-Chasseneuil, France.
authors: Philippe
authors: P
authors: Traoré
authors: Departamento de Física Aplicada III, Universidad de Sevilla, ESI, Camino de los Descubrimientos s/n, 41092 Sevilla, Spain.
authors: Pedro A
authors: PA
authors: Vázquez
authors: Departamento de Electrónica y Electromagnetismo, Universidad de Sevilla, Facultad de Física, Avenida Reina Mercedes s/n, 41012 Sevilla, Spain.
authors: Alberto T
authors: AT
authors: Pérez