Drag force on an oscillating object in quantum turbulence

Fujiyama, Shoji; Tsubota, Makoto

doi:10.1103/physrevb.79.094513

Cited by 23 publications

(26 citation statements)

References 28 publications

(47 reference statements)

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“…This behavior is qualitatively consistent with the observations [59]. In order to characterize the transition to turbulence, Fujiyama et al also studied the drag force [63]. The drag force acting on an object in a uniform flow is generally represented by…”

Section: Quantum Turbulence Created By Vibrating Structuressupporting

confidence: 77%

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Quantum hydrodynamics

Tsubota¹,

Kobayashi²,

Takeuchi³

2013

Physics Reports

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154

181

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Quantum hydrodynamics in superfluid helium and atomic Bose-Einstein condensates (BECs) has been recently one of the most important topics in low temperature physics. In these systems, a macroscopic wave function (order parameter) appears because of Bose-Einstein condensation, which creates quantized vortices. Turbulence consisting of quantized vortices is called quantum turbulence (QT). The study of quantized vortices and QT has increased in intensity for two reasons. The first is that recent studies of QT are considerably advanced over older studies, which were chiefly limited to thermal counterflow in 4 He, which has no analogue with classical traditional turbulence, whereas new studies on QT are focused on a comparison between QT and classical turbulence. The second reason is the realization of atomic BECs in 1995, for which modern optical techniques enable the direct control and visualization of the condensate and can even change the interaction; such direct control is impossible in other quantum condensates like superfluid helium and superconductors. Our group has made many important theoretical and numerical contributions to the field of quantum hydrodynamics of both superfluid helium and atomic BECs. In this article, we review some of the important topics in detail. The topics of quantum hydrodynamics are diverse, so we have not attempted to cover all these topics in this article. We also ensure that the scope of this article does not overlap with our recent review article (arXiv:1004.5458), "Quantized vortices in superfluid helium and atomic Bose-Einstein condensates", and other review articles.

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Section: Quantum Turbulence Created By Vibrating Structuressupporting

confidence: 77%

“…Such a simulation was performed by Fujiyama et al as shown in Fig. 6 [63]. The sphere oscillates horizontally; the diameter of the sphere is 3 µm, the frequency of the oscillation is 1590 Hz, while the oscillation velocity is chosen in the range of 30-90 mm/s.…”

Section: Quantum Turbulence Created By Vibrating Structuresmentioning

confidence: 99%

Quantum hydrodynamics

Tsubota¹,

Kobayashi²,

Takeuchi³

2013

Physics Reports

Self Cite

154

181

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“…Since the velocity is usually much lower than the Landau critical velocity of approximately 50 m/s, the transition to turbulence should come not from intrinsic nucleation of vortices but from the extension or amplification of remnant vortices. Such behavior is shown in the numerical simulation by the vortex filament model [49,50,51].…”

Section: Qt Created By Vibrating Structuresmentioning

confidence: 66%

“…By measuring the average of the period, we can know the mean lifetime of QT created by the generator. The mean lifetime increases exponentially with the injection power of the generator to reach the order of 10 3 s. However, the above numerical simulation [50,51] cannot reproduce this behavior, especially such a long lifetime. If we stop supplying vortices to the oscillating sphere, the tangle around it disappears immediately.…”

Section: Qt Created By Vibrating Structuresmentioning

confidence: 92%

Turbulence in quantum fluids

Tsubota¹

2014

J. Stat. Mech.

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Abstract. This paper reviews briefly the recent important developments in the physics of quantum turbulence (QT) in superfluid helium and atomic Bose-Einstain condensates (BECs). After giving basics of quantum hydrodynamics, we discuss energy spectrum, QT created by vibrating structures, visualization among topics on superfluid helium. For atomic BECs we review three-dimensional QT, two-component BECs, and spin turbulence in spinor BECs. The last part is devoted to some perspectives of this issue.

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“…This reveals that the vortex line density in the wire path remains constant during turbulence generation. Simulations of vortex loops attached to an oscillating object 15,24 suggest that the motions of the wire create a vortex tangle by stretching vortex loops in the path while vortex loops cascade to smaller loops by reconnection, namely, a Richardson cascade, and annihilate to a dissipation regime at high Kelvin wave numbers or sufficiently small vortex rings can escape from the wire path. Consequently, the energy flux from vortex creation to dissipation maintains a constant vortex line density in the path.…”

mentioning

confidence: 99%

Critical behavior of steady quantum turbulence generated by oscillating structures in superfluidH4e

et al. 2010

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We report the critical behavior of steady quantum turbulence in superfluid 4 He. By using a thin vibrating wire with no bridge vortices in the superfluid, we find that lifetime of turbulent state for a given driving force reveals an exponential distribution. The mean lifetime estimated from the distribution decreases exponentially but greatly below a critical injection power. We estimate the vortex line density in the turbulent state and find that this critical behavior arises when the interdistance between vortex lines becomes as large as the turbulent region.Superfluid turbulence has attracted renewed experimental and theoretical interest as a result of recent investigations. 1 Turbulence in superfluid 4 He at very low temperatures consists only of a tangle of quantized vortex lines that defines superfluid flow. Hence, the energy flux in superfluid turbulence is described by the motions of the vortex lines. The energy of flows circulating vortex cores cascades from large vortex loops to smaller loops by reconnection ͑Richardson cascade͒; Kelvin waves with scales smaller than the vortex line spacing form along vortex lines and transfer energy from large wavelengths to smaller wavelengths ͑Kelvin wave cascade͒. 2-4 Consequently, the turbulence energy cascades from large scales to small scales, eventually dissipating at high wave numbers. This process can be observed in the decay of the density of vortex lines in superfluid helium 5,6 even at very low temperatures where the normal-fluid component is almost absent.Motions of vortex lines are also manifested in the continuous generation of turbulence by oscillating structures in superfluid 4 He. Experimental studies using oscillating spheres, 7 wires, 8,9 grids, 10 and tuning forks 11,12 indicate that superfluid turbulence can be generated at oscillating velocities above a critical velocity of about 50 mm/s. Vortex lines form bridges between a structure and its surrounding boundaries and they are shaken by the oscillation, developing into turbulence at velocities exceeding the critical velocity. 13,14 In a previous study, we found that a vibrating wire in the absence of bridge vortices also generates turbulence after vortex rings are applied from a vortex ring generator to the wire. 15 In a turbulent state, the vibrating wire continues to generate vortex lines even when further vortex rings are not applied. At sufficiently high driving forces, the generation seems to continue indefinitely. The wire velocity remains constant during the generation of vortex lines. However, the generation will stop suddenly when the driving force is reduced. After that, the vibrating wire cannot generate turbulence even at high velocities. This behavior is in marked contrast to the responses of other oscillating structures with bridge vortices, with respect to intermittent switching between turbulent flow and laminar flow or, more precisely, potential flow. 16,17 A vibrating wire with no bridge vortices determines the lifetime of the turbulent state in the turbulentto-laminar transitio...

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Drag force on an oscillating object in quantum turbulence

Cited by 23 publications

References 28 publications

Quantum hydrodynamics

Quantum hydrodynamics

Turbulence in quantum fluids

Critical behavior of steady quantum turbulence generated by oscillating structures in superfluidH4e

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