Particle image velocimetry measurements of the velocity profile in HeII forced flow

Xu, Ting; Sciver, S.W. Van

doi:10.1063/1.2756577

Cited by 29 publications

(13 citation statements)

References 10 publications

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“…Reppy (72) used porous media to pin and immobilize the quantized vortices, which allowed for the demonstration of pure superflow in the absence of a pressure gradient. The trapping of ions or electrons by quantized vortices was experimentally confirmed by Schwarz & Donnelly (73) (80), He II forced flow (81), and quantum turbulence (78, 80). Guo et al (82) recently implemented a novel technique to image metastable, excited helium molecules using laser-induced fluorescence.…”

Section: Pinning By Impuritiesmentioning

confidence: 82%

Quantum Turbulence

Paoletti

Lathrop

2011

Annu. Rev. Condens. Matter Phys.

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We examine developments in the study of quantum turbulence with a special focus on clearly defining many of the terms used in the field. We critically review the diverse theoretical, computational, and experimental approaches from the point of view of experimental observers. Similarities and differences between the general properties of classical and quantum turbulence are elucidated. The dynamics and interactions of quantized vortices and their role in quantum turbulence are discussed with particular emphasis on reconnection and vortex ring collapse. A stark distinction between the velocity statistics of quantum and classical turbulence is exhibited and used to highlight a potential analogy between quantum turbulence and magnetohydrodynamic (MHD) turbulence in astrophysical plasmas. Although much of this review pertains to superfluid 4 He (He II), the underlying science is broadly applicable to other quantum fluids such as 3 He-B, type-II superconductors, Bose-Einstein condensates, Weinberg-Salam fields, and grand-unified-theory (GUT) Higgs fields.

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Section: Pinning By Impuritiesmentioning

confidence: 82%

Quantum Turbulence

Paoletti

Lathrop

2011

Annu. Rev. Condens. Matter Phys.

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“…The study by visualization of unsteady/ oscillating flows is a new line of inquiry (64) that could, for example, give valuable contributions to the popular study of the temporal and spatial decay of turbulent flows (1,72). The influence of the boundaries of the experimental volume on the studied quantum flows is also an open issue (68) and it might be interesting to know how vortex tangles behave close to solid walls. The latter possible, future directions of cryogenic flow visualization are further evidence that the discussed techniques are very valuable tools for the analysis of puzzling natural phenomena, whose understanding can lead to useful insights into the underlying physics of many, interconnected research fields.…”

Section: Discussionmentioning

confidence: 99%

Visualization of two-fluid flows of superfluid helium-4

Guo

Mantia

Lathrop

et al. 2014

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

114

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Cryogenic flow visualization techniques have been proved in recent years to be a very powerful experimental method to study superfluid turbulence. Micron-sized solid particles and metastable helium molecules are specifically being used to investigate in detail the dynamics of quantum flows. These studies belong to a well-established, interdisciplinary line of inquiry that focuses on the deeper understanding of turbulence, one of the open problem of modern physics, relevant to many research fields, ranging from fluid mechanics to cosmology. Progress made to date is discussed, to highlight its relevance to a wider scientific community, and future directions are outlined. The latter include, e.g., detailed studies of normal-fluid turbulence, dissipative mechanisms, and unsteady/oscillatory flows. He is used as a coolant for superconducting magnets and infrared detectors (2), to astrophysics, where superfluidity is invoked to explain glitches in the rotation of neutron stars (3, 4) and the formation of cosmic strings (5, 6). More recently, superfluidity has been used to describe the collective behavior of birds (7) and a cosmological model has been used to obtain results relevant to superfluid turbulence (8). The latter form of turbulence, occurring in quantum fluids, is indeed an especially interesting topic because of its quantum peculiarities and its similarity to classical turbulence. Superfluids, in which turbulence can be directly visualized and studied, include superfluid 4 He and atomic Bose-Einstein condensates (9). Due to the limit of small sample volumes, the experimental study of turbulence in Bose-Einstein condensates has hardly begun. The development of visualization techniques applicable to superfluid 4 He is thus essential, if our understanding of quantum turbulence is to make significant progress in the near future.Superfluid 4 He is viewed as consisting of two interpenetrating fluids. The gas of thermal excitations forms the normal component, which can be considered as a viscous fluid. The superfluid component is inviscid and its rotational motion is possible only in the presence of topological defects, in the form of quantized vortex filaments. Turbulence in the superfluid component therefore takes the form of a tangle of quantized vortex lines. Turbulence in the normal fluid is more conventional, although the interaction between the normal fluid and the vortices leads to the nonclassical force of mutual friction between the two fluids. Turbulence in such a system can exhibit a behavior that is similar to that found in a classical fluid; but it may take forms that are unknown in classical fluid mechanics: for example, forms relevant to a fluid in which there is no viscous dissipation, and those that depend on the coexistence of the two fluids. Study of quantum turbulence can therefore enrich our knowledge of turbulence in general, as well as being interesting in its own right. Visualization TechniquesFlow visualization techniques have been developed to a high degree of precision and speed for clas...

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“…4͒ and in liquid helium II itself. [5][6][7][8][9] This technique has great potential in the study of superfluid turbulence, a problem which is receiving renewed attention 10,11 also due to advances in the related context of 3 He. 12,13 The PIV technique consists of tracking the motion of small, micron-size inertial particles using lasers; in the limit of small particle size, the observed trajectories of inertial particles in conventional fluids should correspond to the trajectories of fluid parcels.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of solid particles in a tangle of superfluid vortices at low temperatures

2008

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We present results of numerical study of motion of micron-size, neutrally buoyant, solid particles in liquid helium at temperatures small enough that the normal fluid is negligible and turbulence manifests itself as a tangle of superfluid line vortices. Based on dynamically self-consistent model of interaction between a solid particle and the quantized vortex, we analyze first an influence of temperature on particle trapping on the vortex core. We find that the particle can be trapped only in the case where the particle experiences the damping force, such as the viscous drag force exerted by the normal fluid. However, at temperature below 0.7 K, when the normal fluid is practically absent, the moving particle still experiences the damping force caused by the ballistic scattering of quasiparticles ͑phonons and rotons͒ off the particle surface. Using, together with our calculation of close interaction between the particle and the quantized vortex, available experimental data and theoretical results for this force, we show that trapping of micron-size, neutrally buoyant particles on quantized vortices becomes impossible at temperatures below 0.5 K. At such temperatures, the particle motion in the vortex tangle can be studied based on the simpler, "one-way coupling" model ignoring the backreaction of the particle on the motion and evolution of quantized vortices. Based on such a model, we present results of numerical calculation of particle trajectories in the vortex tangle and show that, due to instability of trajectories and the mismatch of initial velocities of particles and the fluid, the motion of inertial particles does not reveal the motion of turbulent superfluid. We show that particle trajectories between vortex cores are ballistic. Interaction of particles with moving vortices leads to increase of the average particle velocity until it saturates at the value much larger than the fluid rms velocity. These results prevent the use of small tracer particles to study vortex tangles at low temperatures, but open to investigation a new and remarkably simple model of Lagrangian turbulence. We present the probability density function of the turbulent velocity and show that the particle velocity spectrum obeys a simple scaling law.

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Particle image velocimetry measurements of the velocity profile in HeII forced flow

Cited by 29 publications

References 10 publications

Quantum Turbulence

Quantum Turbulence

Visualization of two-fluid flows of superfluid helium-4

Dynamics of solid particles in a tangle of superfluid vortices at low temperatures

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