314,344 research outputs found
Guiding-center dynamics of vortex dipoles in Bose-Einstein condensates
A quantized vortex dipole is the simplest vortex molecule, comprising two
counter-circulating vortex lines in a superfluid. Although vortex dipoles are
endemic in two-dimensional superfluids, the precise details of their dynamics
have remained largely unexplored. We present here several striking observations
of vortex dipoles in dilute-gas Bose-Einstein condensates, and develop a
vortex-particle model that generates vortex line trajectories that are in good
agreement with the experimental data. Interestingly, these diverse trajectories
exhibit essentially identical quasi-periodic behavior, in which the vortex
lines undergo stable epicyclic orbits.Comment: 4 pages, 2 figure
Vortex formation and instability in the left ventricle
We study the formation of the mitral vortex ring during early diastolic
filling in a patient-specific left ventricle (LV) using direct numerical
simulation. The geometry of the left ventricle is reconstructed from Magnetic
Resonance Imaging (MRI) data of a healthy human subject. The left ventricular
kinematics is modeled via a cell-based activation methodology, which is
inspired by cardiac electro-physiology and yields physiologic LV wall motion.
In the fluid dynamics videos, we describe in detail the three-dimensional
structure of the mitral vortex ring, which is formed during early diastolic
filling. The ring starts to deform as it propagates toward the apex of the
heart and becomes inclined. The trailing secondary vortex tubes are formed as
the result of interaction between the vortex ring and the LV wall. These vortex
tubes wrap around the circumference and begin to interact with and destabilize
the mitral vortex ring. At the end of diastole, the vortex ring impinges on the
LV wall and the large-scale intraventricular flow rotates in clockwise
direction. We show for the first time that the mitral vortex ring evolution is
dominated by a number of vortex-vortex and vortex-wall interactions, including
lateral straining and deformation of vortex ring, the interaction of two vortex
tubes with unequal strengths, helicity polarization of vortex tubes and
twisting instabilities of the vortex cores
Vortex profiles and vortex interactions at the electroweak crossover
Local correlations of Z-vortex operators with gauge and Higgs fields (lattice
quantum vortex profiles) as well as vortex two-point functions are studied in
the crossover region near a Higgs mass of 100 GeV within the 3D SU(2) Higgs
model. The vortex profiles resemble certain features of the classical vortex
solutions in the continuum. The vortex-vortex interactions are analogous to the
interactions of Abrikosov vortices in a type-I superconductor.Comment: talk at LATTICE99(electroweak), 3 pages and 5 EPS figure
Evidence of Vortex Jamming in Abrikosov Vortex Flux Flow Regime
We report on dynamics of non-local Abrikosov vortex flow in mesoscopic
superconducting Nb channels. Magnetic field dependence of the non-local voltage
induced by the flux flow shows that vortices form ordered vortex chains.
Voltage asymmetry (rectification) with respect to the direction of vortex flow
is evidence that vortex jamming strongly moderates vortex dynamics in
mesoscopic geometries. The findings can be applied to superconducting devices
exploiting vortex dynamics and vortex manipulation, including superconducting
wires with engineered pinning centers.Comment: 5 pages, 3 figure
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