Leapfrogging Kelvin waves

Hietala, Niklas; Hänninen, Risto; Salman, Hayder; Barenghi, Carlo F.

doi:10.1103/physrevfluids.1.084501

Cited by 8 publications

(5 citation statements)

References 29 publications

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“…We note, however, that vortex waves have been seen to transfer to nearby vortices. 40 Eventually this process can bring the whole volume to a quasiuniform state with all vortices having similar Kelvin-wave spectrum. Generation of Kelvin waves from vortex motion along a dissipative surface could thus effectively lead to enhanced dissipation in the whole volume via Silaev's mechanism.…”

Section: Possible Sources Of Finite Friction At T →mentioning

confidence: 99%

Mutual friction in superfluid He−B3 in the low-temperature regime

Mäkinen

Eltsov

2018

Phys. Rev. B

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We measure the response of a rotating sample of superfluid 3 He-B to spin-down to rest in the zerotemperature limit. Deviations from perfect cylindrical symmetry in the flow environment cause the initial response to become turbulent. The remaining high polarization of vortices along the rotation axis suppresses the turbulent behavior and leads to laminar late-time response. We determine the dissipation during laminar decay at (0.13 − 0.22)Tc from the precession frequency of the remnant vortex cluster. We extract the mutual friction parameter α and confirm that its dependence on temperature and pressure agrees with theoretical predictions. We find that the zero-temperature extrapolation of α has pressure-independent value α(T = 0) ∼ 5 · 10 −4 , which we attribute to a process where Kelvin waves, excited at surfaces of the container, propagate into the bulk and enhance energy dissipation via overheating vortex core-bound fermions.

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Section: Possible Sources Of Finite Friction At T →mentioning

confidence: 99%

Mutual friction in superfluid He−B3 in the low-temperature regime

Mäkinen

Eltsov

2018

Phys. Rev. B

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“…They both have essential influence on the dynamics only when ǫ = 0. If ǫ = 0 then a simple phase factor as W n = Θ n exp(iαt/2) removes the terms with α from the system, resulting in well-known equations which are used for modeling longwave dynamics of weakly curved, nearly parallel vortex filaments in a uniform perfect fluid (see, e.g., [33][34][35][36], and references therein):…”

Section: Solutions At ǫ =mentioning

confidence: 99%

Stable and Unstable Vortex Knots in a Trapped Bose Condensate

Ruban

2018

J. Exp. Theor. Phys.

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The dynamics of a quantum vortex torus knot TP,Q and similar knots in an atomic Bose-Einstein condensate at zero temperature in the Thomas-Fermi regime has been considered in the hydrodynamic approximation. The condensate has a spatially nonuniform equilibrium density profile ρ(z, r) due to an external axisymmetric potential. It is assumed that z * = 0, r * = 1 is a maximum point for function rρ(z, r), with δ(rρ) ≈ −(α − ǫ)z 2 /2 − (α + ǫ)(δr) 2 /2 at small z and δr. Configuration of knot in the cylindrical coordinates is specified by a complex 2πP -periodic functionIn the case |A| ≪ 1 the system is described by relatively simple approximate equations for re-scaled functions Wn(ϕ) ∝ A(2πn + ϕ), where n = 0, . . . , P − 1, and iWn,t = −(Wn,ϕϕ +αWn −ǫW * n )/2− j =n 1/(W * n −W * j ). At ǫ = 0, numerical examples of stable solutions as Wn = θn(ϕ − γt) exp(−iωt) with non-trivial topology have been found for P = 3. Besides that, dynamics of various non-stationary knots with P = 3 was simulated, and in some cases a tendency towards a finite-time singularity has been detected. For P = 2 at small ǫ = 0, rotating around z axis configurations of the form (W0 − W1) ≈ B0 exp(iζ) + ǫC(B0, α) exp(−iζ) + ǫD(B0, α) exp(3iζ) have been investigated, where B0 > 0 is an arbitrary constant, ζ = k0ϕ − Ω0t + ζ0, k0 = Q/2, Ω0 = (k 2 0 − α)/2 − 2/B 2 0 . In the parameter space (α, B0), wide stability regions for such solutions have been found. In unstable bands, a recurrence of the vortex knot to a weakly excited state has been noted to be possible.

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“…A number of papers have been written on different aspects of this problem, ranging from the stability (Love 1894;Hicks 1922;Acheson 2000;Tophøj & Aref 2013) to the deformation of the vortex cores and to the effects of viscosity (Shariff & Leonard 1992) using numerical (Riley & Stevens 1993;Borisov 2014;Cheng & Lim 2015) as well as experimental methods (Maxworthy 1972;Yamada & Matsui 1978;Lim 1997;Qin, Liu & Xiang 2018). The most recent developments concern leapfrogging of vortex bundles (Wacks, Baggaley & Barenghi 2014) and helical waves (Hietala et al 2016;Selçuk, Delbende & Rossi 2018;Quaranta et al 2019).…”

Section: Introductionmentioning

confidence: 99%