We resolve a controversial issue of the stability of composite vortex solitons in self-focusing saturable nonlinear media. Stable vortex solitons with hidden angular momentum, i.e., composed of counter-rotating beams with topological charges +1 and −1, are found, and their linear-stability region is identified. In contrast, the solitons with explicit vorticity are always unstable against splitt...

Instantaneous, two-dimensional velocity measurements were conducted in the axial plane of a selfsimilar turbulent axisymmetric jet. The velocity fields were high-pass filtered to expose the vortical structures. An automated method was used to identify the radial and axial coordinates of the vortex centers and rotational sense, and to measure their size, circulation, vorticity, and energy. New i...

The stability of steady, inviscid vortex pairs in equilibrium with a circular cylinder are studied by discretizing equations derived from contour dynamics. These flows were found previously using different methods in Elcrat, Fornberg, Horn & Miller (2000). There are two families of vortices, one with a pair of counter-rotating vortices standing behind the cylinder, which may be thought of as de...

Numerical simulations are used to study an under-expanded sonic jet injected into a supersonic crossflow and an over-expanded supersonic jet injected into a subsonic crossflow, where the flow conditions are based on Santiago et al.’s (1997) and Beresh et al.’s (2005) experiments, respectively. A finite volume compressible Navier–Stokes solver developed by Park & Mahesh (2007) for unstructured g...

Numerical simulations are used to study an under-expanded sonic jet injected into a supersonic crossflow and an over-expanded supersonic jet injected into a subsonic crossflow. A finite volume compressible Navier–Stokes solver developed by Park & Mahesh (2007) for unstructured grids is used. The flow conditions are based on Santiago et al.’s (1997) and Beresh et al.’s (2005) experiments for son...

The dynamics of vortices in a 2D Heisenberg antiferromagnet with an easy-plane anisotropy is studied numerically within the discrete spin model as well as analytically within a continuum approximation based on a suitable extension of the relativistic nonlinear σ model. We find that two like vortices scatter at 90 • during a head-on collision, whereas a vortex-antivortex pair is annihilated into...

A catalogue of nonlinear vortex structures associated with acoustic-gravity perturbations in the Earth’s atmosphere is presented. Besides the previously known KelvinStewart cat’s eyes, dipolar and tripolar structures, new solutions having the form of a row of counter-rotating vortices, and several weakly two-dimensional vortex chains are given. The existence conditions for these nonlinear struc...

It is shown experimentally that free shear flows can be substantially altered through 134) > t direct control of the large coherent vortices present in the flow. First, flow-visualization experiments are conducted in Kalliroscope fluid at Reynolds number 550. A foil is placed in the wake of a D-section cylinder, sufficiently far behind 160" the cylinder so that it does not interfere with the vo...

The mixing properties of a transverse jet are important to a variety of engineering applications. This study seeks to develop actuation strategies that manipulate the geometry and rate of mixing between jet and crossflow, based on a mechanistic understanding of vorticity structure and evolution. Previous studies have shown that vorticity from both the jet boundary layer and the channel wall bou...

Matter-wave interferometers are, in principle, orders of magnitude more sensitive than their optical counterparts. Nevertheless, creation of matter-wave currents to achieve such a sensitivity is a continuing challenge. Here, we propose the use of Optical Angular Momentum (OAM) induced vortex superpositions in Bose-Einstein Condensates (BECs) as an alternative to atom interferometers for gyrosco...