Magnetic fluid flow phenomena in DC and rotating magnetic fields

An investigation of magnetic fluid experiments and analysis is presented in three parts: a study of magnetic field induced torques in magnetorheological fluids, a characterization and quantitative measurement of properties relating to the transition of a ferrofluid drop from a continuous phase into a discrete phase and also into a spiral flow, and a study of magnetic field induced ferrofluid flow reversals. The torque exerted on a spindle filled with magnetorheological fluid (MR fluid) and placed inside a uniform rotating magnetic field is measured with varying rotating magnetic field amplitude and frequency, total fluid volume, and MR fluid volume ratio. When compared to similar ferrofluid torque measurements where the torque increased with rotating magnetic field frequency, the torque frequency dependence of the MR fluid decreases with increasing magnetic field frequency. A simple analysis determines the dependence of the magnetic body torque on particle size to describe the different behavior between the ferrofluid and MR fluid. When a fluorocarbon based ferrofluid is contained between two glass plates separated by a small gap (Hele-Shaw cell) and excited by an applied uniform rotating magnetic field first and then a DC axial magnetic field, a phase like transition occurs that transforms the ferrofluid drop from a continuous phase to a discrete phase. Considering the dominant energy in the configuration to be contributed from the magnetostatic energy of the DC magnetic field and interfacial surface energy, a calculus of minimization of free energy is performed to determine the number of smaller ferrofluid drops that will result from the transition and the threshold axial magnetic field for the transition to occur.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Rhodes, Scott E. (Scott Edward), 1981-

Advisor dc:contributor.advisor

• Markus Zahn.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/17670

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/17670