2010/04/15 by Wei Guo, Sidney B. Cahn, James A. Nikkel +2 · 1 citation
Physics and Astronomy · #physics.flu-dyn #cond-mat.other #physics.atm-clus #quant-ph
paper · pdf · doi:10.1103/physrevlett.105.045301
published as Phys. Rev. Lett. 105, 045301 (2010) · 6 pages, 4 figures. Supplementary information is included.
arxiv created 2010/04/15 · arxiv updated 2010/07/22
Heat is carried in superfluid He-4 by the motion of the normal fluid1, a counterflowing superfluid component serving to eliminate any net mass flow. It has been known for many years that above a critical heat current the superfluid component in this counterflow becomes turbulent. This turbulence takes the form of a disorganized tangle of quantized vortex lines and is maintained by the relative motion of the two fluids2-3. It has been suspected that the normal fluid may also become turbulent4, but experimental verification is difficult without a technique for visualizing the flow. Here we report a series of visualization studies on the normal-fluid component in a thermal counterflow performed by imaging the motion of seeded metastable helium molecules using a laser-induced-fluorescence technique5-8. We present evidence that the flow of the normal fluid is indeed turbulent, at least at relatively large velocities. Thermal counterflow in which both components are turbulent presents us with a new and theoretically challenging type of turbulent behaviour.