Inviscid diffusion of vorticity in low-temperature superfluid helium

Rickinson, Em; Parker, N. G.; Baggaley, Andrew W.; Barenghi, Carlo F.

doi:10.1103/physrevb.99.224501

Cited by 6 publications

(8 citation statements)

References 42 publications

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“…For the data shown in our Fig. 2, we get ν ′ /κ ≃ 0.3, which is close to the simulated values (51,52).…”

Section: Vortex Diffusion Statisticssupporting

confidence: 87%

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Superdiffusion of quantized vortices uncovering scaling behavior of quantum turbulence

Tang,

Bao,

Guo

2021

Preprint

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Generic scaling laws, such as the Kolmogorov's 5/3-law, are milestone achievements of turbulence research in classical fluids. For quantum fluids such as atomic Bose-Einstein condensates, superfluid helium, and superfluid neutron stars, turbulence can also exist in the presence of a chaotic tangle of evolving quantized vortex lines. However, due to the lack of suitable experimental tools to directly probe the vortex-tangle motion, so far little is known about possible scaling laws that characterize the velocity correlations and trajectory statistics of the vortices in quantum-fluid turbulence (QT). Acquiring such knowledge could greatly benefit the development of advanced statistical models of QT. Here we report an experiment where a tangle of vortices in superfluid 4 He are decorated with solidified deuterium tracer particles. Under experimental conditions where these tracers follow the motion of the vortices, we observed an apparent superdiffusion of the vortices. Our analysis shows that this superdiffusion is not due to Lévy flights, i.e., long-distance hops that are known to be responsible for superdiffusion of random walkers. Instead, a previously unknown power-law scaling of the vortex-velocity temporal correlation is uncovered as the cause. This finding may motivate future research on hidden scaling laws in QT.

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“…For the data shown in our Fig. 2, we get ν ′ /κ ≃ 0.3, which is close to the simulated values (51,52).…”

Section: Vortex Diffusion Statisticssupporting

confidence: 87%

“…It is worthwhile noting that the spatial spreading of a decaying isolated vortex tangle at T =0 K either near a solid surface (51) or in bulk He II (52) has been simulated. The growth of the tangle diameter d as reported in Ref.…”

Section: Vortex Diffusion Statisticsmentioning

confidence: 99%

Superdiffusion of quantized vortices uncovering scaling behavior of quantum turbulence

Tang,

Bao,

Guo

2021

Preprint

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“…The growth of the tangle diameter d as reported in ref. 52 exhibits a normal diffusion regime at large t and a clear superdiffusion regime at small t with a fitted scaling of about d 2 ∝ t 1.74 (note that the authors interpreted this latter regime as the ballistic regime). This similarity is encouraging, although our work focuses on the trajectory statistics of vortices in a steady tangle at finite temperatures.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, following ref. 52, we can use our data in the normal diffusion regime to evaluate the effective diffusion coefficient ν /κ = 3 ∆x 2 (t) /4t. For the data shown in our Fig.…”

Section: Resultsmentioning

confidence: 99%

Superdiffusion of quantized vortices uncovering scaling laws in quantum turbulence

Tang

Bao

Guo

2021

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

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Generic scaling laws, such as Kolmogorov’s 5/3 law, are milestone achievements of turbulence research in classical fluids. For quantum fluids such as atomic Bose–Einstein condensates, superfluid helium, and superfluid neutron stars, turbulence can also exist in the presence of a chaotic tangle of evolving quantized vortex lines. However, due to the lack of suitable experimental tools to directly probe the vortex-tangle motion, so far little is known about possible scaling laws that characterize the velocity correlations and trajectory statistics of the vortices in quantum-fluid turbulence, i.e., quantum turbulence (QT). Acquiring such knowledge could greatly benefit the development of advanced statistical models of QT. Here we report an experiment where a tangle of vortices in superfluid 4He are decorated with solidified deuterium tracer particles. Under experimental conditions where these tracers follow the motion of the vortices, we observed an apparent superdiffusion of the vortices. Our analysis shows that this superdiffusion is not due to Lévy flights, i.e., long-distance hops that are known to be responsible for superdiffusion of random walkers. Instead, a previously unknown power-law scaling of the vortex–velocity temporal correlation is uncovered as the cause. This finding may motivate future research on hidden scaling laws in QT.

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“…The importance of the diffusion mechanism for the decay of inhomogeneous tangle was studied theoretically 51 and numerically [52][53][54] for the decaying tangles at T = 0 K with most recent estimates of the effective diffusion constant in the range (0.1 − 1)κ. The presence of dissipative walls reduces 53 the values of the effective diffusion constant, while in the 3D unbounded vortex tangle 54 the value of the effective diffusion constant was found to be close to 0.5κ.…”

Section: G Effective Diffusivitymentioning

confidence: 99%

Dynamics of turbulent plugs in a superfluid He4 channel counterflow

Pomyalov

2020

Phys. Rev. B

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Quantum turbulence in superfluid He-4 in narrow channels often takes the form of moving localized vortex tangles. Such tangles, called turbulent plugs, also serve as building blocks of quantum turbulence in wider channels. We report on a numerical study of various aspects of the dynamics and structure of turbulent plugs in a wide range of governing parameters. The unrestricted growth of the tangle in a long channel provides a unique view on a natural tangle structure including superfluid motion at many scales. We argue that the edges of the plugs propagate as turbulent fronts, following the advection-diffusion-reaction dynamics. This analysis shows that the dynamics of the two edges of the tangle have distinctly different nature. We provide an analytic solution of the equation of motion for the fronts that define their shape, velocities and effective diffusivity, and analyze these parameters for various flow conditions. arXiv:2002.05002v2 [cond-mat.other]

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Inviscid diffusion of vorticity in low-temperature superfluid helium

Cited by 6 publications

References 42 publications

Superdiffusion of quantized vortices uncovering scaling behavior of quantum turbulence

Superdiffusion of quantized vortices uncovering scaling behavior of quantum turbulence

Superdiffusion of quantized vortices uncovering scaling laws in quantum turbulence

Dynamics of turbulent plugs in a superfluid He4 channel counterflow

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