Characteristics of Two-Dimensional Quantum Turbulence in a Compressible   Superfluid
  Under suitable forcing a fluid exhibits turbulence, with characteristics strongly affected by the fluid's confining geometry. Here we study two-dimensional quantum turbulence in a highly oblate Bose-Einstein condensate in an annular trap. As a compressible quantum fluid, this system affords a rich phenomenology, allowing coupling between vortex and acoustic energy. Small-scale stirring generates an experimentally observed disordered vortex distribution that evolves into large-scale flow in the form of a persistent current. Numerical simulation of the experiment reveals additional characteristics of two-dimensional quantum turbulence: spontaneous clustering of same-circulation vortices, and an incompressible energy spectrum with $k^{-5/3}$ dependence for low wavenumbers $k$ and $k^{-3}$ dependence for high $k$. 
T. W. Neely, A. S. Bradley, E. C. Samson, S. J. Rooney, E. M. Wright,   K. J. H. Law, R. Carretero-Gonz\'alez, P. G. Kevreki...
cond-mat.quant-gas