The Effects Due to an Oblique Applied Field

Abstract

The analysis of the foregoing chapters was restricted to the case of a transverse magnetic field, and the basis for the results was the striking parallelism between this particular class of hydromagnetic flows and conventional gas dynamic flows. For an arbitrary orientation of the magnetic field, magnetohydrodynamic wave phenomena are much more complicated, and, in fact, there exist three sound speeds, i.e., modes of propagation, called fast, slow and intermediate waves, in each direction which, moreover, depend on the direction of propagation. The anisotropic nature of magnetohydrodynamic wave propagation was noted first by Herlofson [56] and by van de Hulst [57]. An introductory discussion may be found, for example, in the papers by Friedrichs [1], Grad [58] and Shercliff [55].