Mechanically Versus Thermally Generated Quantum Turbulence of 4He Superflow

Babuin, Simone; Varga, E.; Stammeier, Mathias; Skrbek, L.

doi:10.1007/s10909-012-0835-9

Cited by 2 publications

(1 citation statement)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We notice that, despite the data from the three experiments at the same temperature being roughly consistent within error bars, the superflow data for D10 lie systematically lower than those for D7, which puts pressure on the understanding that ν ′ should not depend on flow details. At any rate, as we have discussed in our works which include determination of effective viscosity [53,54], the absolute value of ν ′ obtained from decay measurements can have uncertainties up to a factor of 4, depending on how strictly the assumption on saturation of the large eddies size attains. Accurate experimental determination of ν ′ to better than a factor of 4 remains therefore still a challenge.…”

Section: Resultsmentioning

confidence: 96%

Quantum turbulence of bellows-driven4He superflow: Steady state

et al. 2012

Self Cite

View full text Add to dashboard Cite

We report on studies of quantum turbulence with second-sound in superfluid 4 He in which the turbulence is generated by the flow of the superfluid component through a wide square channel, the ends of which are plugged with sintered silver superleaks, the flow being generated by compression of a bellows. The superleaks ensure that there is no net flow of the normal fluid. In an earlier paper [Phys. Rev. B, 86, 134515 (2012)] we have shown that steady flow of this kind generates a density of vortex lines that is essentially identical with that generated by thermal counterflow, when the average relative velocity between the two fluids is the same. In this paper we report on studies of the temporal decay of the vortex-line density, observed when the bellows is stopped, and we compare the results with those obtained from the temporal decay of thermal counterflow re-measured in the same channel and under the same conditions. In both cases there is an initial fast decay which, for low enough initial line density approaches for a short time the form t −1 characteristic of the decay of a random vortex tangle. This is followed at late times by a slower t −3/2 decay, characteristic of the decay of large "quasi-classical" eddies. However, in the range of investigated parameters, we observe always in the case of thermal counterflow, and only in a few cases of high steady-state velocity in superflow, an intermediate regime in which the decay either does not proceed monotonically with time or passes through a point of inflexion. This difference, established firmly by our experiments, might represent one essential ingredient for the full theoretical understanding of counterflow turbulence.

show abstract

Section: Resultsmentioning

confidence: 96%