Dresden 2006 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 35: Ferro Fluids / Liquid Chrystals
DY 35.8: Vortrag
Mittwoch, 29. März 2006, 16:15–16:30, SCH 251
The surface relief of the Rosensweig instability – experimental and numerical results compared quantitatively — •Christian Gollwitzer1, Gunar Matthies2, Reinhard Richter1, Ingo Rehberg1, and Lutz Tobiska3 — 1Experimentalphysik V, Universität Bayreuth, 95440 Bayreuth, Germany — 2Ruhr-Universtät Bochum, Universitätsstraße 150, — 3Institut für Analysis und Numerik, Otto-von-Guericke-Universität Magdeburg, PF 4120, D-39106 Magdeburg
The surface of a magnetic fluid exposed to a normal magnetic field above a threshold Bc forms a pattern of hexagonal crests [1]. We record the full three-dimensional surface profile recently made possible by the attenuation of an X-ray beam [2]. This enables us to compare the amplitude and shape of the peak pattern in an extended container with those obtained from numerical simulations [3]. We have measured 540 surface reliefs under adiabatic increase and decrease of the magnetic induction. The measured nonlinear magnetization law and material parameters have been taken into account in the simulations. Very good qualitative agreement with the experiment is found for both the pattern amplitude and the shape of the peaks. Very good quantitative agreement within the statistical errors is achieved with almost no adjustable parameter. “Almost” will be explained in the talk. Fourier decomposition of the shape exposes, that most (≈ 90%) of the energy is in the first Fourier mode.
[1] M. D. Cowley and R. E. Rosensweig, J. Fluid Mech. 30, 671 (1967).
[2] R. Richter and J. Bläsing, Rev. Sci. Instrum. 72, 1729 (2001).
[3] G. Matthies and L. Tobiska, JMMM 289, 346 (2005).