Regensburg 2002 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 13: Ferrofluide

DY 13.4: Vortrag

Montag, 11. März 2002, 12:30–12:45, H3

Faraday instability on ferrofluids in a horizontal magnetic field — •Vladislav Mekhnoshin and Adrian Lange — Institut für Theoretische Rhysik, Universität Magdeburg, Postfach 4120, D-39016, Magdeburg, Germany

The linear stability analysis of the free surface of a horizontally unbounded ferrofluid layer of arbitrary depth subjected to vertical vibrations and a horizontal magnetic field has been performed. A dispersion relation is derived and the stability of the fluid surface with respect to parametrically driven standing waves is considered.

The dependencies of the threshold amplitude of the vibrations on the excitation frequency and the magnetic field are investigated for different depths of the layer in a wide range of the fluid viscosity. The horizontal magnetic field breaks the rotational symmetry of the problem. Therefore predictions about the most unstable patterns can be made within the linear theory. It is shown that rolls either parallel or perpendicular to the field or rhombic patterns can be a first unstable pattern of Faraday waves, depending on the magnetic field and the depth of the fluid layer. A scaling law is suggested, which allows one to map all obtained data in a single plot, where the scaled amplitude of the vibrations is presented as a function of the dimensionless depth of the fluid.