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E. Kim (HAO, NCAR), D.W. Hughes (Dept. of Applied Maths. Univ. of Leeds), A.M. Soward (Dept. of Maths. Univ. of Exeter)
As a step towards constructing a physically realistic model of a fast dynamo, we study numerically the nature of the kinematic dynamo driven by convection in a rapidly rotating cylindrical annulus. Convection maintains the quasi-geostrophic balance whilst developing more complicated time-dependence as the Rayleigh number is increased. We incorporate the effects of Ekman suction and investigate dynamo action resulting from two chaotic flows obtained in this manner. We examine an ``effective'' growth rate as a function of magnetic Prandtl number Pm (proportional to the magnetic Reynolds number). Even for the largest value of Pm considered, a clearly identifiable asymptotic behaviour is not established. Nevertheless, the available evidence is suggestive of a fast dynamo process.
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