CONVECTION IN A ROTATING CYLINDRICAL ANNULUS IN THE PRESENCE OF A MAGNETIC-FIELD

The effect of radial and azimuthal components of a magnetic held on th e convection columns in the fluid filled gap between two cylinders rot ating rigidly about their common vertical axis is investigated numeric ally. The inner cylinder is cooled, the outer one heated such that the buoyancy force driving the convection is provided by the centrifugal force. Bur the analysis applies also in the planetary case a here the effective components of gravity and of the temperature gradient are re versed. Because of conical end surfaces of the annular gap, the convec tion columns drift relative to the rotating frame of reference. The ma gnetic field exerts a stabilizing influence on the onset of convection and on the onset of secondary instabilities leading to stationary mea n flow convection or to time dependent vacillating convection. Of part icular interest are the cases of merging stability regions when double minima of the neutral curve exist.