Superfluid vortex turbulence on a curved surface – VORTECS

The VORTECS (superfluid VORtex TurbulencE on a Curved Surface) project is a joint theory-experiment effort to investigate superfluid dynamics on the surface of a bubble. It aims first at evidencing long-wavelength Rossby waves and zonal (azimuthal) flows driven by a latitude-dependent Coriolis force, a superfluid analogue of atmospheric hydrodynamics. The relevant parameters can be varied over a wide range on the experimental platform: the rotation speed from subsonic to hypersonic and the latitude from the south pole to the equator. Second, in order to access individual vortex trajectories, we will implement a non destructive, in situ, high resolution imaging scheme. We will also develop an effective kinetic model describing a dilute vortex gas to gain quantitative understanding of the energy and momentum redistribution processes. This will give access to the dynamics of large vortex clusters, a crucial feature of two-dimensional turbulence. The kinetic model will help guiding the experiment to reach and characterize turbulent states. Finally the interplay of curvature, rotation, large-scale instabilities and vortex dynamics will be evidenced in the competition between vortex clustering and formation of large scale azimuthal flows.