THE INFLUENCE OF A HOMOGENEOUS MAGNETIC-FIELD ON THE EKMAN AND STEWARTSON LAYERS

This contribution is aimed at a comparison of two different methods of hour to deal with the solid inner core in geodynamo models. The first method, based on a direct application of the non-slip boundary condit ions, was frequently used in the past. The second one, developed by th e authors of the present paper, is based on an advanced analytical sol ution within the boundary layers and consequent formulation of new bou ndary conditions on the flow in the volume of the outer core. As an ex ample we have used the results obtained by Hollerbach (1997) in the st udy of the influence of an imposed axial magnetic field on the fluid f low in a differentially rotating spherical shell. In the case of a wea k imposed magnetic field, our solutions are very similar to those of H ollerbach. This non-trivial correspondence confirms the correctness of both methods, which are different not only in the formulation of boun dary conditions, but also in the numerical methods: whereas Hollerbach used spectral methods, our computer code is based on finite differenc es. The influence of the conductivity of the inner core on the fluid f low was also studied.