Dresden 2006 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.115: Poster

Donnerstag, 30. März 2006, 16:00–18:00, P1

Preventing the Rayleigh-Taylor instability in ferrofluids — •Dirk Rannacher and Andreas Engel — Carl-von-Ossietzky Universität, 26111 Oldenburg, Germany

Whenever a dense, heavy fluid is layered on a light fluid the plane interface between the two immiscible fluids becomes unstable, the denser fluid moves down under the influence of the gravitational force and the lighter fluid is displaced upwards. This instability is called the Rayleigh-Taylor instability.

We consider a system of two superimposed, immiscible, viscous fluids with densities ρ₁ for the lower and ρ₂>ρ₁ for the upper fluid, where the upper one is a ferrofluid.

Ferrofluids are stable suspensions of magnetic particles and a suitable liquid carrier. A magnetic field H stabilizes a flat surface of a ferrofluid by suppressing surface modulations when the magnetic field is parallel to the wave vector k of this modulation [1]. Consequently to stabilize a two dimensional surface a rotating magnetic field is proposed.

A linear stability analysis shows, that the instability of a two dimensional flat interface between a ferrofluid and a non-magnetic fluid can be stabilized by a parallel, rotating magnetic field.

[1] R. E. Rosensweig, Ferrohydrodynamics, (Cambridge University Press, Cambridge, 1985)