Superfluide à Haut Reynolds en Ecoulement de von Karman – SHREK

This project exploits the capacities of a high cooling power refrigerator for implementing a large dimensions von Karman flow (diameter 80 cm), working as well with liquid or gaseous helium, as with superfluid. Von Karman flow is producted between two parallel contrarotating disks. It is now well documented. Recent progress has been realised on the understanding of the mean flow structures. Depending on the location, it presents either a reasonable example of homogeneous isotropic turbulence, or an interesting case of strong anisotropy. P. Tabeling et al. already used cryogenic helium in a von Karman flow, and obtained the main known results on superfluid turbulence. A traditional weak point of cryogenic turbulence experiments is the small number of available probes. We shall develop an original instrumentation (hot wire, second sound tweezers, acoustic scattering, ...) allowing to probe the flow at any scale, from the mean flow to sub-inertial scales. Comparing the normal and super-fluid behaviours in the same geometry will provide an original way to test some controversed ideas about turbulence. An asset to this ambitious project is that each participant is interested in everything, from the design of the experiment to the results analysis.