Theory of ultrasonic attenuation in magnetic fluids

Recent ultrasonic measurements have yielded anomalous results for the velocity and attenuation in magnetic fluids as a function of the applied field. Thus far, the experimental results have not been satisfactorily explained by a theoretical model. In the present paper, starting with Tarapov´s ferrohydro-dynamical equations, we attempt to derive an expression for the ultrasonic attenuation. Numerical calculations, with adjustable parameters, give fairly good agreement between theory and experiment for attenuation versus field angle.