HR: 16:15h
AN: SH32D-02    [PDF]
TI: A Variational Principle For MHD Waves In Non-Uniform Flows
AU: * Webb, G M
EM: gmwebb@citrus.ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California, Riverside, 900 University Ave., Room 1432, Geology Bldg., Riverside, CA 92521 United States
AU: Zank, G P
EM: zank@ucrac1.ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California, Riverside, 900 University Ave., Room 1432, Geology Bldg., Riverside, CA 92521 United States
AU: Kagashvili, E K
EM: ekagash@citrus.ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California, Riverside, 900 University Ave., Room 1432, Geology Bldg., Riverside, CA 92521 United States
AU: Ratkiewicz, R E
EM: roma@cbk.waw.pl
AF: Space Research Center, Bartyca 18A, Warsaw, 00-716 Poland
AB: A variational approach for the propagation of linear MHD waves in a non-uniform background flow, such as the solar wind is developed. The analysis is based on the work of Dewar (1970) who used an averaged Lagrangian method to describe the interaction of WKB, MHD waves with a non-uniform background flow. Dewar's variational principle is used to describe non-WKB, MHD waves in a non-uniform background flow,including the effects of gravity and entropy wave disturbances.The equations consist of coupled wave equations for the Lagrangian fluid displacement, $\xi$, representing the Alfv\'en and magnetoacoustic waves, and the entropy advection equation for the Lagrangian entropy perturbation $\Delta S$. In the case of steady background flows, with no entropy wave perturbations, the equations reduce to related equations used by Frieman and Rotenberg (1960) to study the stability of steady MHD flows.The characteristics of the equations are obtained by determining the characteristic manifolds on which the Cauchy problem for the waves does not have a unique solution. The characteristics are used to discuss the characteristics and Mach cone for steady MHD flows. A discussion is also given of stress energy tensors for the waves and background flow.
DE: 2149 MHD waves and turbulence
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting