Crow instability of vortex lines in dipolar superfluids

Fuente: arXiv
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Auteurs principaux: Prasad, Srivatsa B., Parker, Nick G., Baggaley, Andrew W.
Format: Preprint
Publié: 2024
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author Prasad, Srivatsa B.
Parker, Nick G.
Baggaley, Andrew W.
author_facet Prasad, Srivatsa B.
Parker, Nick G.
Baggaley, Andrew W.
contents In classical inviscid fluids, antiparallel vortices perturbed by Kelvin waves exhibit the Crow instability, where the mutual interaction of the Kelvin modes renders them dynamically unstable. This results in the approach and reconnection of the vortices, leading to a cascaded decay into ever-smaller vortex loops. Through mean-field simulations we study the Crow instability of quantum vortex lines in a superfluid whose atoms are subject to the anisotropic, long-ranged dipole-dipole interaction. We observe that the direction of dipole polarization plays a crucial role in determining the dynamically favored Kelvin modes. The subsequent rate of the instability is linked to the mediation of the vortex curvature by the effective dipole-dipole interaction between the vortices themselves. The vortex curvature is strongly suppressed and modes of lower wavenumber are preferred when the dipole polarization is parallel to the vortices, whereas the curvature is maximized for polarizations along the vortices' separation axis. For polarizations along the binormal axis, modes of higher wavenumber are favorable but the instability rate is considerably inhibited. This paves the way to a deeper understanding of vortex reconnections, vortex loop cascades and turbulence in dipolar superfluids.
format Preprint
id arxiv_https___arxiv_org_abs_2407_04177
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Crow instability of vortex lines in dipolar superfluids
Prasad, Srivatsa B.
Parker, Nick G.
Baggaley, Andrew W.
Quantum Gases
Fluid Dynamics
In classical inviscid fluids, antiparallel vortices perturbed by Kelvin waves exhibit the Crow instability, where the mutual interaction of the Kelvin modes renders them dynamically unstable. This results in the approach and reconnection of the vortices, leading to a cascaded decay into ever-smaller vortex loops. Through mean-field simulations we study the Crow instability of quantum vortex lines in a superfluid whose atoms are subject to the anisotropic, long-ranged dipole-dipole interaction. We observe that the direction of dipole polarization plays a crucial role in determining the dynamically favored Kelvin modes. The subsequent rate of the instability is linked to the mediation of the vortex curvature by the effective dipole-dipole interaction between the vortices themselves. The vortex curvature is strongly suppressed and modes of lower wavenumber are preferred when the dipole polarization is parallel to the vortices, whereas the curvature is maximized for polarizations along the vortices' separation axis. For polarizations along the binormal axis, modes of higher wavenumber are favorable but the instability rate is considerably inhibited. This paves the way to a deeper understanding of vortex reconnections, vortex loop cascades and turbulence in dipolar superfluids.
title Crow instability of vortex lines in dipolar superfluids
topic Quantum Gases
Fluid Dynamics
url https://arxiv.org/abs/2407.04177