Group 6

Nonlinear Dynamical Analysis of Ferrofluid

Ferrofluid exibits nonlinear dynamical behavior in response to both static and oscillating external magnetic fields. An experiment was developed to isolate a single peak response of ferrofluid to an electromagnetic field generated by a hertzien coil. The apparatus was configured such that a single peak could be isolated. The response was observed with a highspeed camera. First a static magnetic field was applied. This resulted in nonlinear surface behavior accompanied by a hysteresis effect. Spontaneous peak formation was observed at a critical field magnitude. We have examined this response and related an established qualitative model. A critical magnitude is observed in which spontaneous peak formation is induced (normal field instability). Subcritical instability is also observed and results in characteristically different peaks. Next, a thermal component was intruced and a corrosponding term was added to the dynamical equation to account for this effect. This nonlinear surface oscillating bifurcation is rarely studied or observed.

Experimental Apparatus

Parts list

1. Hertzion Coil
2. Teflon Fluid Holder
3. Power Supply
4. High-speed Camera
5. Ferrofluid - EFH-1

Experimental Procedure

File:E1

References

T. Mahr and I. Rehberg, "Nonlinear dynamics of a single ferrofluid-peak in an oscillating magnetic field," Physica D, vol. 111, pp. 335-346, Jan 1998.