Ultrasonic Attenuations in Magnetic Fluids

Experiments of ultrasonic attenuation have been performed in a water-based magnetic fluid by pulse-echo method. A 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. Complicated results were obtained when the attenuation was plotted as a function of the magnetic field strength and angles. So far no existing theoretical model gives satisfactory explanation for these results. In this paper, we attempted to derive expressions for the attenuation from the ferrohydrodynamical equations of Tarapov. Numerical calculations give fairly good agreement between the theory and the experiment with adjustable parameters.

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