  We examine the dynamics of a vortex dipole in the Bose-Einstein condensates
(BECs) of trapped dilute atomic gases at zero temperature in the presence of a
Gaussian barrier potential. The density-anisotropy induced by the barrier
enhances the acoustic radiation from the vortex dipole. This is due to the
deviation of the condensate density from the equipotential curves and variation
in the curvature of the vortex dipole trajectory. Due to the acoustic
radiation, the vortex dipole dissipates energy and spirals towards the edge of
the condensate. As a result, we observe an increase in the vortex-antivortex
annihilation events. To examine the effect of the Gaussian barrier, we estimate
the correction to the Thomas-Fermi condensate density using perturbation
expansion method and the results are in very good agreement with the numerical
results.
