Rotation of a Tangle of Quantized Vortex Lines in He II

Swanson, Charles E.; Barenghi, Carlo F.; Donnelly, Russell J.

doi:10.1103/physrevlett.50.190

Cited by 71 publications

(107 citation statements)

References 10 publications

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“…Thus, an important question arose: what happens if vortices are created by both rotation and counterflow along the rotational axis? Only one experiment seems to address this issue [44]. In the experiment, Swanson, Barenghi, and Donnelly mounted a counterflow channel on a rotating cryostat, thus being able to create vortices by independent combination of rotation and counterflow.…”

Section: F Rotating Superfluid Turbulencementioning

confidence: 99%

“…We used periodic boundary conditions along the rotating axis and rigid boundary conditions at the side-walls. Also, the counterflow was applied along the z-axis, the normal fluid was assumed to be at rest in the rotating frame, and, to make comparison with the experiment [44], we did the calculation for a temperature T = 1.6 K. Hence, the calculation included mutual friction. Two quantities were introduced to characterize the vortex tangle.…”

Section: F Rotating Superfluid Turbulencementioning

confidence: 99%

“…To better understand these flow regimes, we simulated the original experiments of Swanson et al [44], in which the superfluid flowed in a rotating cube, and found that the ordering of the vortex array was sensitive to the rotation velocity. In a rotating cube, the equation of motion of vortices is modified by two effects.…”

Section: F Rotating Superfluid Turbulencementioning

confidence: 99%

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Dynamics of Quantized Vortices in Superfluid Helium and Rotating Bose-Einstein Condensates

Tsubota

Kasamatsu

2005

J Low Temp Phys

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In this article, we review the research on the dynamics of quantized vortices in superfluid helium and rotating Bose-Einstein condensates with emphasis on the recent research done by our group. A quantized vortex is a topological defect that arises from the order parameter in Bose-Einstein condensation in which frictionless superfluid flows with quantized circulation around each vortex.A quantized vortex was both predicted and discovered first in superfluid 4 He which was the first example of a Bose-Einstein condensate. Quantized vortices have been thoroughly studied in superfluid 4 He; one of the principal problems was the superfluid turbulent state consisting of a tangle of quantized vortices in thermal counterflow. More recently, the interest has shifted to the nature of superfluid turbulence, apart from the case of counterflow. After briefly reviewing the earlier research and describing the current problems, we focus our review on superfluid turbulence and vortex filament dynamics. One of the important problems is how superfluid turbulence relates to classical turbulence. Superfluid turbulence was recently shown to have an energy spectrum consistent with the Kolmogorov law, which is an important statistical law in fully developed classical turbulence. We also describe the diffusion of an inhomogeneous vortex tangle with relation to the observed decay of vortices at very low temperatures where the normal fluid component is so negligible that the usual mutual friction does not work as a decay mechanism. In connection to the above discussion of groups of vortices, we describe the vortex states that appear in a rotating channel with counterflow. Rotational effects cause the vortices to form ordered arrays, whereas counterflow effects tend to cause disordered vortex tangles; the competition of these two effects makes a new state of "a polarized vortex tangle" which opens up superfluid phase diagrams as a new area of study.In the specific field of atomic-gas Bose-Einstein condensation, we discuss recent numerical analysis of the Gross-Pitaevskii equation that describes the structure and dynamics of the order parameter. Consistent with observations, the simulated condensate starts an elliptic oscillation after the rotation is turned on, which induces the surface-mode excitations. The vortices develop from these surface excitations and then enter the bulk condensate, eventually forming a vortex lattice. When a condensate is held in a quadratic-plus-quartic combined potential, the fast rotation makes "a giant vortex" in which most vortices are absorbed into a central hole around which the superflow circulates.

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Section: F Rotating Superfluid Turbulencementioning

confidence: 99%

Section: F Rotating Superfluid Turbulencementioning

confidence: 99%

Section: F Rotating Superfluid Turbulencementioning

confidence: 99%

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Dynamics of Quantized Vortices in Superfluid Helium and Rotating Bose-Einstein Condensates

Tsubota

Kasamatsu

2005

J Low Temp Phys

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“…However, if a vortex line has large enough tangential component along the counterflow there may appear Kelvin-waves that eventually can lead to instabilities [2][3][4] . These instabilities together with vortex reconnections favor a turbulent state that is seen in experiments at temperatures below 0.6T c .…”

Section: Introductionmentioning

confidence: 99%

Superfluid 3He-B Vortex Simulations inside a Rotating Cylinder

2005

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We study numerically vortex dynamics in superfluid 3 He-B by solving the full Biot-Savart equations inside a rotating cylinder. The initial vortex configuration seems to have an essential role whether the growth process starts or not. The growth process is, at least at the early stages of simulations, mostly governed by the reconnections with cylinder boundary. In order to see a large increase in vortex density one should go below 0.5T c in temperature, somewhat lower than what is observed in the experiments.

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“…One particular consequence is that, if the meridional circulation is fast enough, a vortex tangle (superfluid turbulence) is alternatively created and destroyed in the outer core of the star (and indeed any spherical container). For example, before a glitch, differential rotation in the outer core drives a non-zero, poloidal counterflow which excites the Donnelly-Glaberson instability (DGI) (Glaberson, Johnson & Ostermeier 1974;Swanson, Barenghi & Donnelly 1983;Tsubota, Araki & Barenghi 2003), and the vortices evolve into an isotropic tangle of reconnecting loops. In this regime, the friction force is of GM form, coupling the normal and superfluid components loosely.…”

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confidence: 99%

Superfluid spherical Couette flow

et al. 2008

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We solve numerically for the first time the two-fluid Hall-Vinen-BekarevichKhalatnikov (HVBK) equations for an He-II-like superfluid contained in a differentially rotating spherical shell, generalizing previous simulations of viscous spherical Couette flow (SCF) and superfluid Taylor-Couette flow. The simulations are conducted for Reynolds numbers in the range 1 × 10 2 6 Re 6 3 × 10 4 , rotational shear 0.1 6 Ω/Ω 6 0.3, and dimensionless gap widths 0.2 6 δ 6 0.5. The system tends towards a stationary but unsteady state, where the torque oscillates persistently, with amplitude and period determined by δ and Ω/Ω. In axisymmetric superfluid SCF, the number of meridional circulation cells multiplies as Re increases, and their shapes become more complex, especially in the superfluid component, with multiple secondary cells arising for Re > 10 3 . The torque exerted by the normal component is approximately three times greater in a superfluid with anisotropic Hall-Vinen (HV) mutual friction than in a classical viscous fluid or a superfluid with isotropic Gorter-Mellink (GM) mutual friction. HV mutual friction also tends to 'pinch' meridional circulation cells more than GM mutual friction. The boundary condition on the superfluid component, whether no slip or perfect slip, does not affect the large-scale structure of the flow appreciably, but it does alter the cores of the circulation cells, especially at lower Re. As Re increases, and after initial transients die away, the mutual friction force dominates the vortex tension, and the streamlines of the superfluid and normal fluid components increasingly resemble each other. In non-axisymmetric superfluid SCF, three-dimensional vortex structures are classified according to topological invariants. For misaligned spheres, the flow is focal throughout most of its volume, except for thread-like zones where it is strain-dominated near the equator (inviscid component) and poles (viscous component). A wedge-shaped isosurface of vorticity rotates around the equator at roughly the rotation period. For a freely precessing outer sphere, the flow is equally strain-and vorticity-dominated throughout its volume. Unstable focus/contracting points are slightly more common than stable node/saddle/saddle points in the viscous component, but not in the inviscid component. Isosurfaces of positive and negative vorticity form interlocking poloidal ribbons (viscous component) or toroidal tongues (inviscid component) which attach and detach at roughly the rotation period. 222

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Rotation of a Tangle of Quantized Vortex Lines in He II

Cited by 71 publications

References 10 publications

Dynamics of Quantized Vortices in Superfluid Helium and Rotating Bose-Einstein Condensates

Dynamics of Quantized Vortices in Superfluid Helium and Rotating Bose-Einstein Condensates

Superfluid 3He-B Vortex Simulations inside a Rotating Cylinder

Superfluid spherical Couette flow

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