Attenuation of Sound in Suspensions and Emulsions

Abstract

The absorption of sound in suspensions and emulsions, which can be several orders of magnitude greater than that in the pure substances, usually has been attributed to viscous dissipation processes including relative motion, the relaxing bulk modulus of the suspended material, or scattering. A description of these processes is contained in a more general theoretical treatment, which, in addition, indicates that thermal conduction in the vicinity of the interfaces results in substantial sound attenuation. The theoretical results will be discussed for viscous, compressible, thermal-conducting media and compared to observed experimental ultrasonic absorption behavior in a number of aqueous emulsions and suspensions. [This research was supported in part by the U. S. Office of Naval Research and the National Institutes of Health.]