Dresden 2006 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 35: Ferro Fluids / Liquid Chrystals

DY 35.5: Vortrag

Mittwoch, 29. März 2006, 15:30–15:45, SCH 251

Pattern reorientation at the tilted field instability — •Christopher Groh, Reinhard Richter, and Ingo Rehberg — Experimentalphysik 5, Univ. Bayreuth, D-95440 Bayreuth, Germany

We investigate the surface instability of a horizontal layer of magnetic liquid in a magnetic field experimentally. By means of two pairs of orthogonal Helmholtz coils we are able to apply a vertical and a tangential magnetic field. Whereas the vertical component destabilizes the flat layer, the tangential one preserves its stability. In this way different surface patterns can be observed, comprising regular hexagons, stretched hexagons and ridges [1,2]. We measure transitions between these patterns under variation of the field components. The surface reliefs are quantitatively characterized via help of a radioscopic technique [3]. This enables us to present the proper bifurcation diagrams and phase diagrams for the tilted field instability. Moreover, we report a new effect: the rotation of the hexagonal pattern under a increasing tangential field component.

[1] Rene Friedrichs, Phys. Rev. E 66, 066215 (2002).

[2] Bert Reimann, Reinhard Richter, Holger Knieling, Rene Friedrichs, and Ingo Rehberg, Phys. Rev. E. 71 1(R) (2005).

[3] Reinhard Richter, and Jürgen Bläsing, Rev. Sci. Instrum. 72, 1729 (2001).