Compared to hydrodynamic (HD) waves in a nonmagnetized fluid,
magnetohydrodynamic (MHD) waves in a magnetized fluid show
complicated behavior.
Here we present the results
of
2-dimensional MHD numerical simulations and explain the basic properties
of MHD waves.
Introduction
First of all, we show the dispersion-relation diagram of an HD wave
(sound wave)
and two MHD waves (fast-mode wave, slow-mode wave).
Phase velocity is
the propagation speed of a single-mode wave while group velocity is the
propagation speed of a group of
single-mode waves.
Next we describe the basic setting of the simulations.
Simulation Results
In the following we show wave propagation
in a non-magnetized fluid (HydroDynamic case),
highly magnetized fluid (Low beta case), and
weakly magnetized fluid (High beta
case). Click the picture for details.
HD case (Nonmagnetized case)
Low beta case (beta = 0.5)
(Strong magnetic field)