  The expansion of Bose-Einstein condensates with quantized vortices is studied
by solving numerically the time-dependent Gross-Pitaevskii equation at zero
temperature. For a condensate initially trapped in a spherical harmonic
potential, we confirm previous results obtained by means of variational methods
showing that, after releasing the trap, the vortex core expands faster than the
radius of the atomic cloud. This could make the detection of vortices feasible,
by observing the depletion of the density along the axis of rotation. We find
that this effect is significantly enhanced in the case of anisotropic
disc-shaped traps. The results obtained as a function of the anisotropy of the
initial configuration are compared with the analytic solution for a
noninteracting gas in 3D as well as with the scaling law predicted for an
interacting gas in 2D.
