We fabricated a device that controls the motion of flux quanta in a niobium superconducting film grown on an array of nanoscale triangular pinning potentials. The controllable rectification of the vortex motion is due to the asymmetry of the fabricated magnetic pinning centers. The reversal in the direction of the vortex flow is explained by the interaction between the vortices trapped on the m...

We analyse the currently popular vortex identification criteria that are based on pointwise analysis of the velocity gradient tensor. A new measure of spiralling compactness of material orbits in vortices is introduced and using this measure a new local vortex identification criterion and requirements for a vortex core are proposed. The interrelationships between the different criteria are expl...

Cardiac MR group Lund, Dept. of Clinical Physiology, Lund University, Lund, Sweden Full list of author information is available at the end of the article Figure 1 Design and construction of the vortex ring flow phantom. a) 2D view of the flow rectifier and vortex ring tank. All measures are in millimeters (mm). b) 3D view of the flow rectifier and vortex ring tank. c) Pump design. A servo motor...

Pelagic copepods jump to relocate, to attack prey and to escape predators. However, there is a price to be paid for these jumps in terms of their energy costs and the hydrodynamic signals they generate to rheotactic predators. Using observed kinematics of various types of jumps, we computed the imposed flow fields and associated energetics of jumps by means of computational fluid dynamics simul...

Nonlinear quasigeostrophic flows in two layers over a topographic slope are considered. Scaling the lower layer potential vorticity equation yields two parameters which indicate the degree of nonlinearity in the lower layer. The first, u' (the strength of the deep flow divided by the product of the effective bottom slope and the squared length scale), is related to the advection of relative vor...

Vortices are long-lived features of geophysical and laboratory flows. They emerge in free-decay turbulence and govern the long-term evolution of the flow. In 2D flows, two vortices can grow by merger when they are like-signed. The process of vortex merger in 2D flows is well known for a pair of isolated vortices. Nevertheless, in a turbulent field, the velocity field created by neighboring vort...

This paper investigates vortex shedding processes occurring at the end of a stack of parallel plates, due to an oscillating flow induced by an acoustic standing wave within an acoustic resonator. Here, Particle Image Velocimetry (PIV) is used to quantify the vortex shedding processes within an acoustic cycle phase-by-phase, in particular during the “ejection” of the fluid out of the stack. Stan...

Recent studies have suggested that intracardiac vortex flow imaging could be of clinical interest to early diagnose the diastolic heart function. Doppler vortography has been introduced as a simple color Doppler method to detect and quantify intraventricular vortices. This method is able to locate a vortex core based on the recognition of an antisymmetric pattern in the Doppler velocity field. ...

A technique for observing flow in vortex cores in flight is described and the results of flight tests to study vortex breakdown using the HP 115 aircraft are presented.

Light experiences a non-uniformly moving medium as an effective gravitational field, endowed with an effective metric tensor g̃μν = η μν + (n2 − 1)uμuν , n being the refractive index and uμ the fourvelocity of the medium. Leonhardt and Piwnicki [Phys. Rev. A 60, 4301 (1999)] argued that a flowing dielectric fluid of this kind can be used to generate an ’optical black hole’. In the Leonhardt-Piwn...