The thermally activated vortex bundle flow over the directional-dependent energy barrier in type-II superconductors is investigated. The coherent oscillation frequency and the mean direction of the random collective pinning force of the vortex bundles are evaluated by applying the random walk theorem. The flow velocity of the vortex bundles is obtained self-consistently. The temperatureand fiel...

We reveal that the reduction of the group velocity of light in periodic waveguides is generically associated with the presence of circulating energy flows or optical vortices. We show that the energy flows are gradually frozen for slow-light at the Brillouin zone edge, whereas vortices persist for slow-light states having non-vanishing phase velocity inside the Brillouin zone. We also demonstra...

The propagation velocity and propagation mechanism for vortices on a plane are determined for a reduced-gravity model by integrating the momentum equations over the plane. Isolated vortices, vortices in a background current, and initial vortex propagation from rest are studied. The propagation mechanism for isolated anticyclones as well as cyclones, which has been lacking up to now, is presente...

analysis of the flow passing cylindrical obstacles is one of the basic issues in fluid dynamics and is of great importance. many surveys have been conducted to investigate the velocity field in potential and viscous flows, as a basis for finding pressure field, and investigation of forces exerted by fluid on obstacles such as uplift and drag forces in different flow regimes. since the nature of...

We investigate the pinning and driven dynamics of vortices interacting with twin boundaries using large scale molecular-dynamics simulations on samples with near one million pinning sites. For low applied driving forces, the vortex lattice orients itself parallel to the twin boundary and we observe the creation of a flux gradient and vortex-free region near the edges of the twin boundary. For i...

Ultrasound time-of-flight methods employing counter-propagating ultrasonic pulses are utilized for the direct measurement of circulation in vortical flows. Two schemes are described here which involve either a single straight path or a closed path. Both techniques are shown to result in time differences, between the counter-propagating pulses around the path, linearly proportional to the circul...

Background Intracardiac blood flow is known to influence cardiac development through transduction of endothelial shear forces. Vortex rings inside the left ventricle constitute a possible “blueprint” for cardiogenesis, the hemodynamic determinant of final cardiac shape. However, the relationship between the vortex ring and endocardium has previously not been quantified, and the influence of the...

We prove the existence of steady 2-dimensional flows, containing a bounded vortex, and approaching a uniform flow at infinity. The data prescribed is the rearrangement class of the vorticity field. The corresponding stream function satisfies a semilinear elliptic partial differential equation. The result is proved by maximizing the kinetic energy over all flows whose vorticity fields are rearra...

Influence of a vent hood at the exit of exhaust flue gas and flue baffles in the firetube on the temperature and flow fields of a gas tank water heater, as well as thestructure and amount of heat transferred to the water tank has been studiednumerically using two-dimensional steady state finite element simulation.Observations show that without a vent hood, there is a downward gas flow in theflu...

In two dimensions, vorticity is materially conserved in an invisicid environment. Additionally, if the fluid is nondivergent, the velocity field can be determined from a solution to the Poisson equation relating velocity and vorticity. Vortex methods translate these well-known facts as well as the ability to capture the time evolution of Lagrangian particles into a method of representing the fl...