© 1961 by Oxford University Press
ON THE MAGNETOHYDRODYNAMICS OF ASYMMETRIC SURFACE WAVES IN A DISH OF SHALLOW CONDUCTING LIQUID
( Aeronautics Department, Imperial College London )
This paper describes small disturbances of an inviscid, electrically conducting liquid resting in a circular dish made of insulating material, and subject to a vertical magnetic field. The depth of the liquid is assumed to be much smaller than the diameter of the dish or than a typical wavelength. The response to an initial disturbance is investigated by means of approximate equations which are an extension of the linear shallow-water theory. The mathematical problem is essentially an eigenvalue problem for a fourth-order partial differential equation with mixed space-time derivatives. It is found that, as a result of dissipation by Joule heating, all the modes of the solution are damped, but the initial rate of decay of the lowest asymmetric mode is only about one-sixth that of the axisymmetrio modes. Wave profiles and current lines for a particular asymmetric motion are shown.