Vortex-vortex interactions in toroidally trapped Bose-Einstein   condensates
  We analyze the vortex dynamics and vortex-vortex interactions in Bose-Einstein condensates confined in toroidal traps. We show that this particular geometry strongly distorts the vortex dynamics. The numerically calculated vortex trajectories are well explained by an analytical calculation based on image method and conformal mapping. Finally, the dissipation effects are discussed. 
T. Schulte, L. Santos, A. Sanpera and M. Lewenstein