  3D MHD global solar simulations coupling the turbulent convective zone and
the radiative zone have been carried out. Essential features of the Sun such as
differential rotation, meridional circulation and internal waves excitation are
recovered. These realistic models are used to test the possibility of having
the solar tachocline confined by a primordial inner magnetic field. We find
that the initially confined magnetic fields we consider open into the
convective envelope. Angular momentum is transported across the two zones by
magnetic torques and stresses, establishing the so-called Ferarro's law of
isorotation. In the parameter space studied, the confinement of the magnetic
field by meridional circulation penetration fails, also implying the failure of
the tachocline confinement by the magnetic field. Three-dimensional convective
motions are proven responsible for the lack of magnetic field confinement.
Those results are robust for the different magnetic field topologies
considered, i.e. aligned or oblique dipole.
