Acoustic perturbations in specialrelativistic parallel flows
Abstract
Acoustic perturbations in a parallel relativistic flow of an inviscid fluid are considered. The general expression for the frequency of the sound waves in a uniformly (with zero shear) moving medium is derived. It is shown that relativity evokes a difference in the frequencies of the soundtype perturbations propagating along and against the current. Besides, it is shown that the perturbations are not purely irrotational as they are in nonrelativistic case. For a nonuniformly (with nonzero shear) moving fluid a general set of equations, describing the evolution of the acoustic perturbations in relativistic sheared flows, is obtained and analysed when the temperature is nonrelativistic. It is shown that, like the nonrelativistic case, in the new system: (a) the excitation of vortical, transiently growing perturbations, and (b) the excitation of soundtype perturbations, extracting the kinetic energy of the background flow, are possible. It is demonstrated that the relativistic character of the motion significantly intensifies the efficiency of both these processes. Finally, the possible relevance of this study to processes in astrophysical shear flows is pointed out.
 Publication:

arXiv eprints
 Pub Date:
 July 1996
 arXiv:
 arXiv:astroph/9607085
 Bibcode:
 1996astro.ph..7085R
 Keywords:

 Astrophysics
 EPrint:
 17 pages, LATEX, no figures