Effective viscosity in quantum turbulence: A steady-state approach

The concept of "effective viscosity" of superfluid helium, widely used to interpret decaying turbulence, is tested in the steady-state case. We deduce from measurements of the vortex line density, , in a grid flow. The scaling of with velocity confirms the validity of the heuristic relatio...

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Bibliographic Details
Published in:Europhysics letters 2014-04, Vol.106 (2), p.24006-12
Main Authors: Babuin, Simone, Varga, Emil, Skrbek, Ladislav, Lévêque, Emmanuel, Roche, Philippe-E.
Format: Article
Language:English
Subjects:
47.37.+q
67.25.dg
67.25.dk
Computational fluid dynamics
Condensed Matter
Decay
Dissipation
Energy dissipation
Engineering Sciences
Fluid flow
Fluid mechanics
Fluids
Fluids mechanics
Liquid helium
Mathematical analysis
Mechanics
Other
Parameter uncertainty
Physics
Quantum Gases
Quantum turbulence
Steady state
Superfluidity
Temperature dependence
Turbulence
Turbulent flow
Viscosity
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Summary:The concept of "effective viscosity" of superfluid helium, widely used to interpret decaying turbulence, is tested in the steady-state case. We deduce from measurements of the vortex line density, , in a grid flow. The scaling of with velocity confirms the validity of the heuristic relation defining , , where is the energy dissipation rate and κ the circulation quantum. Within , is consistent with that from decays, allowing for uncertainties in flow parameters. Numerical simulations of the two-fluid equations yield a second estimation of within an order of magnitude with all experiments. Its temperature dependence, more pronounced in numerics than experiments, shows a crossover from a viscous-dominated to a mutual-friction-based dissipation as temperature decreases, supporting the idea that the effective viscosity of a quantum turbulent flow is an indicator of the dissipative mechanisms at play.
ISSN:0295-5075
1286-4854
DOI:10.1209/0295-5075/106/24006