The Sun and probably many stars rotate differentially - the angular velocity depends on the location. On the other hand, a small magnetic field can turn such a diffrential-rotation flow into turbulence (magnetorotational instability). The turbulent flow will -- sooner or later -- equalize the rotation profile. The present numerical investigations show that this process is very fast and is expected to destroy differential rotation on the rotational time-scale.
The spectral spherical MHD code of Rainer Hollerbach was adapted for this model. The film shown here is one of the first successful simulations. Right now, results from higher-resolution runs are becoming available.
(This picture is part of a movie. You can see the movie by clicking on the image. Be warned: it's 5MB in size!)