  We explore the possible regimes of decaying two-dimensional quantum
turbulence, and elucidate the nature of spectral energy transport by
introducing a dissipative point-vortex model with phenomenological vortex-sound
interactions. The model is valid for a large system with weak dissipation, and
also for systems with strong dissipation, and allows us to extract a meaningful
and unambiguous spectral energy flux associated with quantum vortex motion. For
weak dissipation and large system size we find a regime of hydrodynamic vortex
turbulence in which energy is transported to large spatial scales, resembling
the phenomenology of the transient inverse cascade observed in decaying
turbulence in classical incompressible fluids. For strong dissipation the
vortex dynamics are dominated by dipole recombination and exhibit no
appreciable spectral transport of energy.
