A single peak of the Rosensweig instability

A single peak formed on the free surface of a ferrofluid subject to an over critical magnetic field is investigated both theoretically and experimental ly with respect to its static and dynamic properties. Using a pertubation a nalysis up to fifth order in the surface deflection the static profile of t he surface in the non-linear regime is obtained for the one-dimensional sit uation. If the static magnetic field is superimposed with an oscillating pa rt an intricate pattern of subharmonic response of the peak is found experi mentally. A simple, analytically tractable model is introduced which displa ys qualitative agreement with the experimental results. (C) 1999 Published by Elsevier Science B.V. All rights reserved.