Vortex dynamics in the nonlinear Schrodinger equation
  The dynamics of a two-dimensional vortex are analyzed within the framework of the nonlinear Schrodinger equation. Both a bare vortex and a vortex with an external mass trapped in a finite-sized core are considered. The bare vortex motion is found to be damped at all frequencies, while the finite core has a single resonant frequency. The force exerted by the fluid on the finite core can be expressed as a sum of dissipative and Magnus forces for sufficiently low frequencies, even when the core is small. 
Michael J. Quist