Abstract
Macroscopic surface patterns of magnetic fluids are experimentally
investigated for
four different configurations of the liquid layer, and the orientation,
homogeneity and temporal evolution of
the magnetic field. Firstly the formation of surface undulations after a
pulse-like application of the
magnetic induction is examined. The wavenumbers measured for different
magnetic induction are
compared with the wavenumber of maximal growth predicted by linear
stability analysis for the Rosensweig instability.
Secondly, the formation of twin-peak patterns at the magnetic Faraday
instability in an annular trough
is reported. Thirdly, a ring of magnetic liquid spikes in a gradient
magnetic field is periodically excited
by an alternating magnetic field. The transition to spatio-temporal
intermittency found in this way
is characterized by power laws and their critical exponents. Eventually,
we record the pinch-off of a magnetic
liquid bridge by a high-speed camera. The temporal evolution of the
neck radius is compared with
results obtained theoretically via universal scaling functions.
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