We report on recent experimental efforts to improve the understanding of surface instabilities in magnetic fluids. In the linear regime we focus on the wavenumber of maximal growth, and the oscillatory decay of metastable liquid ridges, experimentally accessible via a new pulse technique. We compare the measurements with the predictions of linear stability analysis.
In the nonlinear regime we are recording the three-dimensional surface profiles by a novel radioscopic measurement technique. These hexagonal Rosensweig patterns are successfuly compared with results achieved by simulations utilizing the finite element method, as well as by results obtained from amplitude equations.
Eventually we are investigating 2D-solitons (ferrosolitons), which could be generated in the bistable regime of the subcritical bifurcation. We probe their range of stability and test their stabilization mechanism. As a first model a conservative analogue to the Swift-Hohenberg-equation is presented, which can explain their existance and stability. By generating several ferrosolitons we are able to study their binding to molecule-like structures.
- http://www.uni-bayreuth.de/departments/ep5/ff.html - survey of current research in the ferrofluid-group
- http://focus.aps.org/story/v15/st18 - 2D-solitons covered on focus