Anisotropy and drift of a vortex tangle in helium II

Wang, R. T.; Swanson, Charles E.; Donnelly, Russell J.

doi:10.1103/physrevb.36.5240

Cited by 49 publications

(33 citation statements)

References 7 publications

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“…8c) < s ′ z > is negligible but not exactly zero (< s ′ z >≈ 0.01), certainly because the driving counterflow is along the z direction. This small anisotropy of the counterflow tangle has been already reported in the literature 28 . At small rotation (Fig.…”

Section: Rotating Turbulencesupporting

confidence: 84%

Instability of vortex array and transitions to turbulence in rotating helium II

et al. 2004

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We consider superfluid helium inside a container which rotates at constant angular velocity and investigate numerically the stability of the array of quantized vortices in the presence of an imposed axial counterflow. This problem was studied experimentally by Swanson et al., who reported evidence of instabilities at increasing axial flow but were not able to explain their nature. We find that Kelvin waves on individual vortices become unstable and grow in amplitude, until the amplitude of the waves becomes large enough that vortex reconnections take place and the vortex array is destabilized. The eventual nonlinear saturation of the instability consists of a turbulent tangle of quantized vortices which is strongly polarized. The computed results compare well with the experiments. Finally we suggest a theoretical explanation for the second instability which was observed at higher values of the axial flow.

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Section: Rotating Turbulencesupporting

confidence: 84%

Instability of vortex array and transitions to turbulence in rotating helium II

et al. 2004

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“…However, the hypothesis of complete isotropy of the tangle is not confirmed by the simulation of the dynamics of the vortex tangle made by Schwarz [15]- [17] and in the experiments [18]. Indeed the particular direction of the counterflow breaks the rotational symmetry in the dynamics.…”

Section: Hvbk Model Evolution Equations For the Normal And The Supermentioning

confidence: 90%

Hydrodynamic equations of anisotropic, polarized and inhomogeneous superfluid vortex tangles

Jou

Mongiovı̀

Sciacca

2011

Physica D: Nonlinear Phenomena

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We include the effects of anisotropy and polarization in the hydrodynamics of inhomogeneous vortex tangles, thus generalizing the well known Hall-Vinen-Bekarevich-Khalatnikov equations, which do not take them in consideration. These effects contribute to the mutual friction force F ns between normal and superfluid components and to the vortex tension force ρ s T. These equations are complemented by an evolution equation for the vortex line density L, which takes into account these contributions. These equations are expected to be more suitable than the usual ones for rotating counterflows, or turbulence behind a cylinder, or turbulence produced by a grid of parallel thin cylinders towed across a superfluid, because in these situations polarization is expected to play a relevant role.

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“…1͒ and of longitudinal second sound. 16 The measure of this anisotropy can be defined with the use of the structure parameters I ʈ , I Ќ introduced by Schwarz ͑see Ref. 13͒ who confirmed the anisotropy of the vortex tangle in the numerical modeling.…”

Section: ͑5͒mentioning

confidence: 99%

Gaussian model of vortex tangle in He II

Nemirovskii

1998

Phys. Rev. B

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A description of the chaotic vortex tangle in superfluid turbulent He II is developed. Unlike current phenomenological theory dealing with only the macroscopic variable, the vortex line density L v (t) and describing thereby only the macroscopic hydrodynamic phenomena, our approach allows us to describe effects due to the arrangement of the vortex tangle and the interaction of lines. To develop this approach we introduce a trial distribution function in the space of vortex loop configurations which absorbs all properties of superfluid turbulence known both from experiment and from numerical simulations. This trial distribution function is built in terms of the path integral. A number of allowed configurations is obtained evaluating the path integral with constraints connected with the established properties of the vortex tangle. Using the trial distribution function we also build the characteristic ͑generating͒ functional which allows us to evaluate any average over the vortex loop configuration. On the basis of the developed approach we briefly discuss some simple statistical characteristics of the vortex tangle. A more extended example of the developed approach studying superfluid mass current induced by vortex tangle is reported in a subsequent paper.

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Anisotropy and drift of a vortex tangle in helium II

Cited by 49 publications

References 7 publications

Instability of vortex array and transitions to turbulence in rotating helium II

Instability of vortex array and transitions to turbulence in rotating helium II

Hydrodynamic equations of anisotropic, polarized and inhomogeneous superfluid vortex tangles

Gaussian model of vortex tangle in He II

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