Rights statement: © 2004 American Physical Society
Accepted author manuscript, 2.75 MB, PDF document
Available under license: CC BY-NC: Creative Commons Attribution-NonCommercial 4.0 International License
Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Article number | 056307 |
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<mark>Journal publication date</mark> | 1/01/2004 |
<mark>Journal</mark> | Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics |
Issue number | 5 |
Volume | 70 |
Number of pages | 1 |
Publication Status | Published |
<mark>Original language</mark> | English |
A systematic experimental investigation of the macroscopic flow properties of extremely pure He II in the zero temperature limit is reported, covering the pressure range [Formula presented]. The flow is generated by electrostatically driven oscillations of a thin, tightly stretched, circular, square-mesh nickel grid. With growing amplitude of oscillation, the flow changes character at a first critical threshold from pure inviscid superflow past a submerged body of hydrodynamically enhanced mass, to a flow regime that is believed to involve a boundary layer composed of quantized vortex loops. Here the oscillatory motion of the grid acquires strongly nonlinear features. These include double-valued (reentrant) resonance curves and a decrease in the resonant frequency with increasing drive amplitude, but without any appreciable increase in damping. On further increase of the drive level, a second critical threshold is attained: here, the resonant frequency reaches a stable value, the response amplitude almost stops growing, but the linewidth increases. Finally, the flow acquires the character of fully developed classical turbulence, characterized by a square-root dependence of flow velocity on the driving force. Additional flow features attributable to the presence of remanent vorticity are observed and discussed.