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Non-axisymmetric magnetohydrodynamic stability of a streaming annular jet containing very dense fluid cylinder and surrounded by a tenuous medium pervaded by a varying azimuthal magnetic field

Published online by Cambridge University Press:  13 March 2009

Ahmed E. Radwan
Affiliation:
Department of Mathematics, Faculty of Science, Ain-Shams University, Abbassia, Cairo, Egypt

Abstract

The magnetohydrodynamic stability of a streaming annular jet containing a very dense fluid cylinder and acted upon by inertial and electromagnetic forces, in the presence of a varying transverse magnetic field pervading a tenuous surrounding medium, is considered. A general dispersion relation is established and studied analytically, and the results are confirmed numerically. The magnetic fields are stabilizing or destabilizing for each of the symmetric (m = 0) and non-axisymmetric (m ≠ 0) modes under some restrictions. The streaming has a strong destabilizing character, and its influence is to enlarge the magnetohydrodynamic instability domains and shrink the stability domains. The thicker the dense fluid core, the greater the number of magneto-hydrodynamically stable states. Increasing the magnetic field intensity shrinks the unstable domains. The (in)stability situation is much worse for m ≠ 0. However, if the axial field intensity is sufficiently high and greater than the transverse field intensity, the destabilizing character of the model, in a few cases, may be suppressed. This occurs if the Alfvén-wave velocities interior and exterior to the annular jet are greater than the unperturbed fluid velocity.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1990

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