We propose very general vortex nucleation mechanismss1] analogous to a hydrodynamic instability and calculate associated critical velocity in agreement with experiments. The creation of vortices via extrinsic mechanism is driven by a formation of the surface vorticity sheet created by the ow, which reaches a critical size. Such a sheet screens an attraction of a half-vortex ring to the wall, th...

in this paper, the flow around bluff bodies with different cross sections and determination of forces acts on them are investigated.this paper presents the results of a numerical study on the flow characteristics and heat transfer over two equal square cylinders in a tandem arrangement. spacing between the cylinders is 5 widths of the cylinder and the reynolds number ranges from 1 to 200, pr=0....

Dynamics of vortex pairs with the same and opposite circulations are studied theoretically in nonlocal nonlinear media with different intervortex separations. We demonstrate that the nonlocal nonlinear response not only leads to a dramatic suppression of the elliptical instabilities but also helps in the formation of quasi-stable rotating and breathing bound states for vortex–vortex and vortex–...

Rankine vortex characteristics of a partially coherent optical vortex are explored using classical and physical optics. Unlike a perfectly coherent vortex mode, the circulation is not quantized. Excess circulation is predicted owing to the wave nature of composite vortex fields. Based on these findings, we propose a vortex stellar interferometer.

2 9 Repetition of the male back-cross test with star dichaete ......................... 290 Location of the vortex genes through linkage tests with star and dichaete.. ..... 292 The localization of vortex I1 by aid of streak .................................. 296 The streak vortex modifier 300 Further tests of the position of vortex I11 301 The isolation of an (additional vortex intensifier.. 3...

Vortex dynamics in coherent ensembles of exciton polaritons (condensates) is studied in the framework of the polarization-dependent Gross-Pitaevskii equation. Vortex lattices can be resonantly excited in the polariton field by the interference of three or more optical pumps. Vortex-antivortex pairs can also appear in polariton condensates due to scattering with disorder. The nonlinear vortex dy...

We discuss an experimental technique developed to visualize quantized vortices in helium II. We illuminate micron-sized solid particles of hydrogen suspended in the fluid, and mark quantized vortex cores within the volume observed by a camera. While, under some circumstances, the particles modify vortex dynamics by the action of viscous drag and by pinning vortex intersections, we do capture ba...

This paper examines two-dimensional vortex motion in a shear-flow with nonuniform vorticity. Typically, a vortex travels to an extremum in the background vorticity distribution. In general, the rate of this migration increases with the magnitude of the background vorticity gradient; however, a retrograde vortex, which rotates against the local shear, moves orders of magnitude faster than a prog...

investigations were carried out to evaluate the performance of direct injection diesel engine with medium grade low heat rejection (lhr) combustion chamber and 3 mm air gap insulated piston, 3 mm air gap insulated liner, and ceramic coated cylinder head [ceramic coating with the thickness of 500 µ was made on the inside portion of the cylinder head].the engine had different operating conditions...