Spatial Confinement Causes Lifetime Enhancement and Expansion of Vortex   Rings with Positive Filament Tension
  We study the impact of spatial confinement on the dynamics of three-dimensional excitation vortices with circular filaments. In a chemically active medium we observe a decreased contraction of such scroll rings and even expanding ones, despite of their positive filament tension. We propose a kinematical model which takes into account the interaction of the scroll ring with a confining Neumann boundary. The model reproduces all experimentally observed regimes of ring evolution, and correctly predicts the results obtained by numerical simulations of the underlying reaction-diffusion equations. 
Jan F. Totz, Harald Engel, Oliver Steinbock
nlin.PS physics.chem-ph