Coherent optical beams may contain optical vortices that are characterized by a dark core and a well-defined azimuthally harmonic phase.1,2 In contrast, different points in a spatially incoherent beam are uncorrelated, and the phase structure of an optical vortex is ill defined. In the transitional regime of partially coherent light, one should take the statistical properties of light into acco...

This thesis reports numerical calculations on quantized vortices in He and He superfluids. Vortices are of crucial importance in understanding many of the superfluid properties. All the calculations presented in the thesis have experimental relevance, either in understanding measured results or in predicting the outcome of planned experiments. Superfluid He has been observed to exhibit incomple...

In the earth’s atmosphere baroclinic instability is responsible for the heat and momentum transport from low to high latitudes. Baroclinic instability leads to the growth of multi-scale vortices that accomplish the meridional heat transport. Raymond Hide used a rather simple laboratory experiment to study such vortices in the lab (Hide, 1953). The experiment is comprised by a cooled inner and h...

One concern in using photonic band-gap fiber (PBGF) as a gas sensor is the response time. In this type of the gas sensors, response time is the time required for gas to diffuse into the hollow-core. So considering a large hollow-core PBGF (HC-PBGF), the response time can be significantly reduced. But in the large HC-PBGF, the fundamental issue is the presence of higher order modes (HOMs). Somet...

Some tests with trapped vortices in supersonic flow-by-SUMMARY An arrangement known briefly as a vortex bearing, or trapped vortex, is described. This was devised initially with the object of improving supersonic air intakes featuring internal compression and focussing of the compression waves at the throat, Tests were made with simple rigs to check various aspects of the performance of such vo...

We study the dispersion relation of Kelvin waves propagating along single- and half-quantum vortices in miscible two-component Bose-Einstein condensates based on analysis Bogoliubov--de Gennes equation. With help interpolating formula connecting relations low- high-wave-number regimes, we reveal nontrivial dependence intercomponent interaction through change vortex-core size vortical component....

s (in alphabetical order) Michael Dallaston (Imperial College London) ”Interfacial Hele-Shaw flows that develop corner singularities” It is well known that the evolution of a receding free boundary in one-phase Hele-Shaw flow (such as an expanding air bubble surrounded by viscous fluid) is ill-posed and generically forms cusps. The interfacial velocity at the cusp points is unbounded. Imposing ...

We report what we believe to be the first demonstration of a laser-driven fiber optic gyroscope (FOG) built with an air-core fiber. Its phase noise is measured to be 130 murad/ radicalHz. When the sensing fiber is replaced with a conventional fiber, this figure drops to 12 murad/ radicalHz. Comparison between these values suggests that the air-core fiber gyro is most likely not limited solely b...

This paper describes the unsteady and three-dimensional characteristics of heat transfer from a circular cylinder to the cross-flow of air for Reynolds numbers from 120 to 30 000. An infrared camera was used to measure the time-spatial characteristics of heat transfer on the cylinder surface, heated under a condition of constant heat flux. Fluctuating heat transfer was measured using a heat flu...

The interaction of vortex patches in relation to the observed scales and features reported in Part I of this paper is investigated. It is found that the initial approach of compound vortices, such as tropical cyclones, arises from distortion of their, weaker, outer vorticity fields. Care needs to be taken in applying simple concepts, such as the propagation of each vortex on the gradient of its...