  We performed 2D and full 3D magnetohydrodynamic simulations of disk accretion
to a rotating star with an aligned or misaligned dipole magnetic field. We
investigated the rotational equilibrium state and derived from simulations the
ratio between two main frequencies: the spin frequency of the star and the
orbital frequency at the inner radius of the disk. In 3D simulations we
observed different features related to the non-axisymmetry of the
magnetospheric flow. These features may be responsible for high-frequency
quasi-periodic oscillations (QPOs). Variability at much lower frequencies may
be connected with restructuring of the magnetic flux threading the inner
regions of the disk. Such variability is specifically strong at the propeller
stage of evolution.
