  Understanding the reasons of the cyclic variation of the total solar
irradiance is one of the most challenging targets of modern astrophysics. These
studies prove to be essential also for a more climatologic issue, associated to
the global warming. Any attempt to determine the solar components of this
phenomenon must include the effects of the magnetic field, whose strength and
shape in the solar interior are far from being completely known. Modelling the
presence and the effects of a magnetic field requires a 2D approach, since the
assumption of radial symmetry is too limiting for this topic. We present the
structure of a 2D evolution code that was purposely designed for this scope;
rotation, magnetic field and turbulence can be taken into account. Some
preliminary results are presented and commented.
