@article{oai:nagoya.repo.nii.ac.jp:00005479,
author = {Menâ€™shov, Igor and Nakamura, Yoshiaki},
issue = {3},
journal = {Physics of Fluids},
month = {Jan},
note = {The normal mode linear analysis is applied to investigate the stability of a circular isolated compressible vortex with the emphasis on studying the effect of entropy stratification of the basic flow on stability properties. We study a family of vortices that have zero total circulation, with the swirl velocity being presented by a Taylor-type distribution in the radial direction. The stratification of entropy is modeled by a Gaussian two-parametric profile whose parameters control the maximal deviation from the homentropic distribution and the extent of the entropic zone. Results presented concern the effect of these parameters and the vortex intensity on instability characteristics. In particular, in the case of homentropic flow, vortices considered are found to be stable only for sufficiently high intensities and cease to be stable as the intensity weakens. As an example of the situation where unstable normal modes can be excited, the scattering of sound waves by the vortex flow is considered. By simulating this process numerically, we show that the scattered field becomes unstable in the course of time and acquires a typical periodical pattern in polar angle. The characteristics of this instability (viz., the growth rate and the azimuthal phase frequency)coincide with those of the linear analysis very closely. This fact shows conclusively that the instability is caused by the induction of unstable normal modes in the vortex by means of sound irradiation.},
pages = {034102--034102},
title = {Instability of isolated compressible entropy-stratified vortices},
volume = {17},
year = {2005}
}