Local measurement of vortex statistics in quantum turbulence

Woillez, Éric; Valentin, J.; Roche, Philippe-Emmanuel

doi:10.1209/0295-5075/134/46002

Cited by 6 publications

(12 citation statements)

References 37 publications

(87 reference statements)

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“…24 displays the selectivity of two second sound tweezers of size L = 250 µm and L = 1 mm respectively, depending on the shift X sh and the mode number n (where k = nπ). The simulation was run with a quantum vortex line density L = 2 × 10 10 m −2 and U = 1 m/s, in accordance with the typical values observed in the experiments of [WVR21]. It can be seen that large tweezers (L = 1 mm) can reach a vortex selectivity R ξ > 90% for a small shift and low mode number, which means that they can be used for direct quantum vortex measurements.…”

Section: Kenelly Circle Centermentioning

confidence: 76%

“…Aside from vortex density measurements, the second sound can also provide information on the fluid temperature -since the second sound velocity depends on it-and on the velocity of the background He-II flow when it induces a phase shift or Doppler effect on the second sound (e.g. see [DL77,WPHE81,WVR21]).…”

Section: From Macroscopic Second Sound Sensors To Microscopic Tweezersmentioning

confidence: 99%

“…The temperature-sensitive material used in the present study is AuSn, which fulfills two requirements: (1) it is compatible with the microfabrication process and (2) it can be tuned to become temperature-sensitive over a range of special interest to quantum turbulence studies [WVR21], from 1.5 K up to the superfluid transition temperature T λ 2.18K in saturated vapor conditions. Surely, other materials would be more appropriate in other conditions, e.g.…”

Section: Thermometrymentioning

confidence: 99%

“…Numerous resistive materials are suitable, e.g. chrome was used for the tweezers in [RDD + 07] and platinum in [WVR21]. Present data have been obtained with platinum to benefit from the temperature-independence of its resistivity at superfluid temperatures [PK82], and nevertheless to allow re-use of these miniature heaters as miniature thermometers or hot-film anemometers in experiments conducted at higher temperatures where Pt regains temperature dependence [Kem91].…”

Section: Heatingmentioning

confidence: 99%

“…This is a strong indication that those type of tweezers can be used as anemometers. The signal fluctuations of those type of tweezers were recently characterized in a turbulent flow of superfluid helium [WVR21]. It has been shown in particular that both the signal spectra and its probability distributions indeed display all the characteristics of that of turbulent velocity fluctuations.…”

Section: Effect Of Lateral Shift Of the Emitter And Receiver Platesmentioning

confidence: 99%

See 4 more Smart Citations

Second sound resonators and tweezers as vorticity or velocity probes : fabrication, model and method

Woillez¹,

Valentin²,

Roche³

2023

Preprint

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An analytical model of second-sound resonators with open-cavity is presented and validated against simulations and experiments in superfluid helium using a new design of resonators reaching unprecedented resolution. The model accounts for diffraction, geometrical misalignments and flow through the cavity. It is validated against simulations and experiments using cavities of aspect ratio of the order of unity operated up to their 20 th resonance in superfluid helium. An important result is that resonators can be optimized to selectively sense the quantum vortex density carried by the throughflow -as customarily done in the literature-or alternatively to sense the mean velocity of this throughflow. Two velocity probing methods are proposed, one taking advantage of geometrical misalignements between the tweezers plates, and another one by driving the resonator non-linearly, beyond a threshold entailing the self-sustainment of a vortex tangle within the cavity.After reviewing several methods, a new mathematical treatment of the resonant signal is proposed, to properly separate the quantum vorticity from the parasitic signals arising for instance from temperature and pressure drift. This so-called elliptic method consists in a geometrical projection of the resonance in the inverse complex plane. Its strength is illustrated over a broad range of operating conditions.The resonator model and the elliptic method are applied to characterize a new design of second-sound resonator of high resolution thanks to miniaturization and design optimization. When immersed in a superfluid flow, these so-called second-sound tweezers provide time-space resolved information like classical local probes in turbulence, here down to sub-millimeter and sub-millisecond scales. The principle, design and micro-fabrication of second sound tweezers are detailed, as well as their potential for the exploration of quantum turbulence Contents * present affiliation: CEA-Liten, Grenoble

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Section: Kenelly Circle Centermentioning

confidence: 76%

Section: From Macroscopic Second Sound Sensors To Microscopic Tweezersmentioning

confidence: 99%

Section: Thermometrymentioning

confidence: 99%

Section: Heatingmentioning

confidence: 99%

Section: Effect Of Lateral Shift Of the Emitter And Receiver Platesmentioning

confidence: 99%

See 3 more Smart Citations

Second sound resonators and tweezers as vorticity or velocity probes : fabrication, model and method

Woillez¹,

Valentin²,

Roche³

2023

Preprint

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Vibrating Microwire Resonators Used as Local Probes of Quantum Turbulence in Superfluid $$^{4}$$He

Midlik,

Goleňa,

Talíř

et al. 2023

J Low Temp Phys

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Spatial distribution of the quantized vortices' tangle in thermally driven round jets of superfluid helium

2023

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Thermally driven flows of superfluid 4He display unique features, often related to the presence of quantized vortices—line singularities embedded in the liquid. Here, we focus on turbulent round jets, experimentally investigated using the flow visualization and second sound attenuation techniques, at Reynolds numbers exceeding 104. These turbulent flows are driven by releasing heat into a small volume of liquid, open to the surrounding bath through a cylindrical nozzle, 2 mm in diameter. Our measurements reveal in unprecedented detail how the tangle of quantized vortices associated with the jets arranges itself in space, for distances ranging from 9 to 34 nozzle diameters, at fluid temperatures between 1.64 and 2.10 K. We specifically find that the vortex tangle spreads in the radial direction, while it dilutes away from the nozzle. Additionally, the tangle density is found to systematically depend on the flow forcing. Two physical interpretations of the observed behavior are proposed, which could motivate further investigations of this peculiar flow. One leads us to conjecture a self-similar functional form of the vortex tangle density across counterflow jets. The other suggests that the position of the superfluid stagnation point—a characteristic feature of counterflow jets—could depend on the flow forcing as well.

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Local measurement of vortex statistics in quantum turbulence

Cited by 6 publications

References 37 publications

Second sound resonators and tweezers as vorticity or velocity probes : fabrication, model and method

Second sound resonators and tweezers as vorticity or velocity probes : fabrication, model and method

Vibrating Microwire Resonators Used as Local Probes of Quantum Turbulence in Superfluid $$^{4}$$He

Spatial distribution of the quantized vortices' tangle in thermally driven round jets of superfluid helium

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