Turbulence in Boundary Flow of Superfluid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts /><mml:none /><mml:mn>4</mml:mn></mml:mmultiscripts></mml:math>Triggered by Free Vortex Rings

Goto, Risa; Fujiyama, Shoji; Yano, Hideo; Nago, Yusuke; Hashimoto, Nozomu; Obara, K.; Ishikawa, Osamu; Tsubota, Makoto; Hata, Tōju

doi:10.1103/physrevlett.100.045301

Cited by 71 publications

(77 citation statements)

References 20 publications

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“…The collision of the sphere with these vortices will give rise to a breakdown of the potential flow. (A similar observation has been made recently by the Osaka group with a vibrating wire colliding with vortex rings causing the flow to become turbulent [11]). The probability for this event to occur is proportional to ∆ a.…”

Section: Statistics Of the Phases Of Potential Flowmentioning

confidence: 62%

Statistics of Intermittent Switching between Potential Flow and Turbulence around an Oscillating Sphere in Superfluid 4He below 0.5 K

Schoepe

2010

J Low Temp Phys

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The flow of superfluid helium at very low temperatures around an oscillating microsphere is known to be unstable slightly above the critical velocity. The flow pattern switches intermittently between potential flow and turbulence. From time series recorded at constant temperature and driving force the statistical properties of the switching phenomenon are discussed. Based on our recent understanding of the critical velocity v c of oscillatory superflows, i.e., v c ∼ √ κ ω, where κ is the circulation quantum and ω is the oscillation frequency, the analysis is being refined now. From the exponential distribution of the lifetimes of the turbulent phases quantitative information on the vortex density L can be inferred such as the distribution and the width of the fluctuations of L. The phases of potential flow show a Rayleigh distribution of the excess oscillation amplitude above the amplitude at turbulent flow. The rms value is found to scale as ω −3/2 .

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Section: Statistics Of the Phases Of Potential Flowmentioning

confidence: 62%

Statistics of Intermittent Switching between Potential Flow and Turbulence around an Oscillating Sphere in Superfluid 4He below 0.5 K

Schoepe

2010

J Low Temp Phys

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“…It has been provided by Goto et al (21) and was based on experiments with two vibrating wires. The wires are actually loops that are driven at resonance by passing an alternating current, I, through them, the loops being situated in a transverse magnetic field, B (Fig.…”

Section: The Nucleation Of Quantum Turbulencementioning

confidence: 99%

Quantum turbulence generated by oscillating structures

Vinen

Skrbek

2014

Proc. Natl. Acad. Sci. U.S.A.

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The paper summarizes important aspects of quantum turbulence that have been studied successfully with oscillating structures. It describes why some aspects are proving hard to interpret, and it outlines the need for new types of experiment and new developments in theoretical and computational work. superfluid helium | quantized vortex linesThis paper is concerned with the generation of quantum turbulence (1-3) in liquid helium by various forms of oscillating structure, such as a cylinder oscillating in a direction normal to its length. Many experiments on the generation of quantum turbulence by such structures have been reported, involving not only cylinders (or wires), but also spheres, tuning forks, and grids. Many of these experiments and their possible interpretation have already been reviewed (4). We are not aiming to produce another conventional review, and we shall not consider all that has been achieved. Instead, our aim is to focus on three particular aspects of this type of work: first, on experiments that have already contributed significantly to our understanding of issues that are, as we see them, of general and fundamental importance; second, on an exposure of the difficulties in interpreting many of the experiments in any real detail, in the way that has been achieved in analogous work on classical fluids; and third, on ways in which we might overcome these difficulties, which are both theoretical and experimental. We shall be concerned ultimately with both superfluid He. There are of course connections between quantum turbulence produced by oscillating structures and more general aspects of such turbulence. The role of remanent vorticity in the nucleation and stability of quantum turbulence is universally important, and, as we discuss in a later section, it is here that experiments with oscillating structures have been particularly instructive. At a more subtle level, there is the question of the extent to which quantum turbulence is similar to classical turbulence. The observation of a Kolmogorov energy spectrum on large length scales (larger than the vortex-line spacing) in homogeneous quantum turbulence is often quoted as evidence for this similarity. As we shall see, some aspects of the quantum turbulence produced by oscillating structures provide additional evidence. However, in contrast to homogeneous turbulence, quantum turbulence produced by an oscillating structure must be strongly influenced by the boundary conditions at a solid wall. As we discuss in a section devoted to the development of quantum turbulence, uncertainty about the boundary conditions relevant to quantum turbulence hinders interpretation of the experiments and calls for renewed experimental and theoretical study.Almost all of the experiments have involved measurements of the fluid dynamical force on the structure as a function of the amplitude of the oscillations. This force can be divided into a drag, which is in phase with the velocity and therefore dissipative, and a force that is in quadrature with the velocity and ...

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“…The sphere was magnetically levitated in superfluid 4 He, and its response with respect to the alternating drive was observed. At low drives, the velocity response v was proportional to the drive F D , taking the ''laminar'' form Subsequently, several groups have experimentally investigated the transition to turbulence in superfluids 4 He and 3 He-B by using grids, 31,[69][70][71][72] wires, [73][74][75][76][77] and tuning forks. 78) The details of the observations are described in a review article.…”

Section: )mentioning

confidence: 99%

Quantum Turbulence

Tsubota

2008

J. Phys. Soc. Jpn.

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The present article reviews the recent developments in the physics of quantum turbulence. Quantum turbulence (QT) was discovered in superfluid 4 He in the 1950s, and the research has tended toward a new direction since the mid 90s. The similarities and differences between quantum and classical turbulence have become an important area of research. QT is comprised of quantized vortices that are definite topological defects, being expected to yield a model of turbulence that is much simpler than the classical model. The general introduction of the issue and a brief review on classical turbulence are followed by a description of the dynamics of quantized vortices. Then, we discuss the energy spectrum of QT at very low temperatures. At low wavenumbers, the energy is transferred through the Richardson cascade of quantized vortices, and the spectrum obeys the Kolmogorov law, which is the most important statistical law in turbulence; this classical region shows the similarity to conventional turbulence. At higher wavenumbers, the energy is transferred by the Kelvin-wave cascade on each vortex. This quantum regime depends strongly on the nature of each quantized vortex. The possible dissipation mechanism is discussed. Finally, important new experimental studies, which include investigations into temperaturedependent transition to QT, dissipation at very low temperatures, QT created by vibrating structures, and visualization of QT, are reviewed. The present article concludes with a brief look at QT in atomic BoseEinstein condensates.

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Turbulence in Boundary Flow of SuperfluidHe4Triggered by Free Vortex Rings

Cited by 71 publications

References 20 publications

Statistics of Intermittent Switching between Potential Flow and Turbulence around an Oscillating Sphere in Superfluid 4He below 0.5 K

Statistics of Intermittent Switching between Potential Flow and Turbulence around an Oscillating Sphere in Superfluid 4He below 0.5 K

Quantum turbulence generated by oscillating structures

Quantum Turbulence

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