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Anomalous attenuation of ultrasound in ferrofluids under the influence of a magnetic fieldUltrasonic wave propagation has been studied in a water-base ferrofluid by pulse-echo methods. A commercial box-car integrator was used to measure the change in attenuation due to an external magnetic field applied at various angles relative to the ultrasonic propagation vector. Anomalous results were obtained when the attenuation was plotted as a function of the magnetic field strength. As the field increased, the attenuation reached a maximum and then decreased to a flat minimum before it approached saturation at a field of 2 KG. This variation of attenuation with magnetic field cannot be explained from the simple picture derivable from the work of McTague on the viscosity of ferrofluids. In no case was the viscosity seen to decrease with field, nor was the oscillatory behavior observed. The results of this study were compared with the theory developed by Parsons.
Document ID
19780048540
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Isler, W. E.
(U.S. Army, Harry Diamond Laboratories, Adelphi, Md.; Howard University Washington, D.C., United States)
Chung, D. Y.
(Howard University Washington, D.C., United States)
Date Acquired
August 9, 2013
Publication Date
March 1, 1978
Subject Category
Acoustics
Accession Number
78A32449
Distribution Limits
Public
Copyright
Other

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