Direct numerical simulation of supercritical annular electroconvection Physical Review E, 76, 026305 (2007) Peichun Tsai [1], Zahir A. Daya [2], Vatche B. Deyirmenjian [1] and Stephen W. Morris [1] [1] Department of Physics, University of Toronto, 60 St. George St., Toronto, Ontario, Canada M5S 1A7. [2] Defence Research & Development Canada, 9 Grove Street, Dartmouth, Nova Scotia, Canada B2Y 3Z7

We use direct numerical simulation to study electrically-driven convection in an annular thin film. The simulation models a laboratory experiment that consists of a weakly conducting, submicron thick liquid crystal film suspended between two concentric electrodes. The film is driven to convect by imposing a sufficiently large voltage across it. The flow is driven by a surface charge density inversion which is unstable to the imposed electrical force. This mechanism is closely analogous to the mass density inversion which is unstable to the buoyancy force in conventional, thermally-driven Rayleigh-Benard convection. The simulation uses a pseudo-spectral method with Chebyshev polynomials in the radial direction and Fourier modes in the azimuthal direction. The numerical results, which are in good agreement with previous experimental data and theoretical predictions, reveal several new insights. The mode competition near a codimension-two point exhibits hysteresis. The primary bifurcation is supercritical for all geometries and for a broad range of fluid parameters.

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