STABILITY OF CYLINDRICAL COUETTE-FLOW OF A RADIALLY POLARIZED DIELECTRIC LIQUID IN A RADIAL TEMPERATURE-GRADIENT

A linear stability analysis is used to predict the onset of convective instability in an annulus of a pure dielectric liquid between two long coaxial cylinders. The liquid experiences a radial temperature gradient and a strong radial ac electric field. When the two cylinders are stationary our analysis gives reasonable agreement with experiment data on silicone oils. If the central cylinder is warmer and is allowed to rotate, the stability of the Couette flow is predicted to vary with the temperature difference DELTAT between the cylinders in a manner that depends markedly on the gap to radius ratio delta = (r2 - r1)/r1 where r1 and r2 are the radii of the inner and outer cylinders. When delta < 10(-4) the critical Taylor number is relatively insensitive to DELTAT but when delta greater-than-or-equal-to 10(-1) a very small temperature difference can completely destabilize the Couette flow.