|project title:||Turbulence in Fluids and Superfluids|
|project leader:||Prof. VIktor Līvov|
|access given (in days):||90|
|access used (in days):||92|
|local host:||Prof. Grisha Volovik|
|home institution:||Dept. of Chemical Physics, The Weizmann Institute of Science|
|country of institution:||Israel|
|starting date (yyyy-mm-dd):||2004-09-01|
This project is closely connected to the experimental effort in LTL, the ULTI site. New class of superfluid turbulence has been recently discovered experimentally by ROTA group under conditions that the normal component is clamped in the container frame due to its high viscosity. In contrast to classical turbulence, the transition to superfluid turbulence has been found to be velocity independent. According to the experiment, a few seed vortices injected into the He-3 B superflow triggered a transition into a state with a turbulent vortex tangle for temperatures T < 0.6 Tc while the same injection at higher temperatures did not create any substantial number of vortices in the final state. In these measurements, the superfluid Reynolds numbers as high as 200 have been reached without any noticeable dependence of the transition temperature on the initial superflow velocity. The goal was to construct the theory of this new phenomenon in superfluid turbulence.
The project resulted in experimental, numerical and theoretical studies of a vortex front propagating into a region of vortex-free flow of rotating superfluid 3He-B: Quantum turbulence in propagating superfluid vortex front V.B. Eltsov, A.I. Golov, R. de Graaf, R. Hanninen, M. Krusius, V.S. L'vov, R.E. Solntsev Phys. Rev. Lett. 99, 265301 (2007). It has been shown that with decreasing temperature the nature of the vortex front changes from laminar, to the semiclassical turbulent and then to the quantum turbulent regime. The experiment conducted at the ULTI provided the first direct measurement of the dissipation rate in turbulent vortex dynamics of 3He-B and demonstrated that in the zero temperature limit the dissipation approaches the finite value. This was the realization of the dissipation anomaly in the superfluid turbulence. The bottleneck effect in the Kolmogorov cascade has been also observed experimentally and explained theoretically.