Shapes of 2D magnetic fluid droplets in a rotating magnetic field

J.-C. Bacri¹ - A. Cebers² - S. Lacis² - R. Perzynski¹

¹ Universite P.M.Curie, 4 place Jussieu, 75252 Paris, Cedex. 05, France
² Institute of Physics, Latvian University, Salaspils-1, LV-2169, Latvia

Abstract
The families of equilibrium figures of 2D magnetic fluid droplets in high-frequency rotating magnetic field are found numerically. The magnetic field energy is calculated by a boundary integral equation technique for nonlinear transformed and smoothed hypocycloidal curves. Comparison between families with different number of spikes shows that the lowest energy corresponds to the "two-spike" shape. A minimum energy calculation shows that for a fixed number of spikes, these spikes arise at a given threshold in the magnetic Bond number. Increasing the magnetic Bond number sharpens the spikes. Finally some conclusions concerning the discrepancy with the experimental results are pointed out. Figs 7, Refs 14.