Measurements of magnetic-field-induced ferrofluid flow and torque in uniform rotating magnetic fields are presented and compared to theoretical analyses in order to understand observed paradoxical behavior. The viscous torque from this fluid flow is measured using a cylindrical Couette viscometer, as a function of magnetic field amplitude, frequency, and direction of rotation. The first set of experiments measures the torque on the outer wall of a polycarbonate spindle that is attached to a viscometer, which functions as a torque meter. The spindle is immersed in the ferrofluid, which is centered in the gap of a three-phase AC 2-pole motor stator winding. Anomalous behavior, such as negative effective viscosity, is demonstrated and discussed. The second set of experiments measures the viscous torque on the inner wall of a hollow spindle attached to the torque meter and filled completely with ferrofluid so that there is no free surface. These measurements show that magnetic fluid effects arise even in the absence of free surfaces. These observations are then shown to agree with a recently derived analysis of spin-up flow in ferrofluids.
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ASME 2002 International Mechanical Engineering Congress and Exposition
November 17–22, 2002
New Orleans, Louisiana, USA
Conference Sponsors:
- Materials Division
ISBN:
0-7918-3640-1
PROCEEDINGS PAPER
Ferrohydrodynamics in Time-Varying Magnetic Fields
Carlos Rinaldi,
Carlos Rinaldi
Massachusetts Institute of Technology, Cambridge, MA
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June-Ho Lee,
June-Ho Lee
Hoseo University, Chung-Nam, Korea
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Adam D. Rosenthal,
Adam D. Rosenthal
Massachusetts Institute of Technology, Cambridge, MA
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Thomas Franklin,
Thomas Franklin
Massachusetts Institute of Technology, Cambridge, MA
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Markus Zahn
Markus Zahn
Massachusetts Institute of Technology, Cambridge, MA
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Carlos Rinaldi
Massachusetts Institute of Technology, Cambridge, MA
June-Ho Lee
Hoseo University, Chung-Nam, Korea
Adam D. Rosenthal
Massachusetts Institute of Technology, Cambridge, MA
Thomas Franklin
Massachusetts Institute of Technology, Cambridge, MA
Markus Zahn
Massachusetts Institute of Technology, Cambridge, MA
Paper No:
IMECE2002-32275, pp. 155-160; 6 pages
Published Online:
June 3, 2008
Citation
Rinaldi, C, Lee, J, Rosenthal, AD, Franklin, T, & Zahn, M. "Ferrohydrodynamics in Time-Varying Magnetic Fields." Proceedings of the ASME 2002 International Mechanical Engineering Congress and Exposition. Materials: Processing, Characterization and Modeling of Novel Nano-Engineered and Surface Engineered Materials. New Orleans, Louisiana, USA. November 17–22, 2002. pp. 155-160. ASME. https://doi.org/10.1115/IMECE2002-32275
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