  We present a numerical method for generating vortex rings in Bose-Einstein
condensates confined in axially symmetric traps. The vortex ring is generated
using the line-source approximation for the vorticity, i.e., the rotational of
the superfluid velocity field is different from zero only on a circumference of
given radius located on a plane perpendicular to the symmetry axis and coaxial
with it. The particle density is obtained by solving a modified
Gross-Pitaevskii equation that incorporates the effect of the velocity field.
We discuss the appearance of density profiles, the vortex core structure and
the vortex nucleation energy, i.e., the energy difference between vortical and
ground-state configurations. This is used to present a qualitative description
of the vortex dynamics.
