Acoustic radiation force on a spherical particle in a viscous heat-conducting fluid .3. Force on a liquid drop

The general expression derived in Part I of this work [J. Acoust. Soc. Am. 101, 713-721 (1997)] for the acoustic radiation force exerted by a sound field on a spherical particle in a viscous heat-conducting fluid is applied here to a liquid drop. To demonstrate dissipative effects clearly, two limiting cases are studied. In both cases, the sound wavelength is taken to be much larger than other characteristic parameters of the system, such as the drop radius and the viscous, and thermal wavelengths both outside and inside the drop. Within this assumption, two reverse situations are considered, in the first of which the dissipative effects are assumed to be weak, and in the second, to be strong. For each of these two cases, three types of incident wave are dealt with: a plane traveling wave, a plane standing wave, and a diverging spherical wave. Emphasis is given to the thermal effects on the radiation force. These are found to be greatest in the traveling and spherical waves, while in the standing wave, for both limiting cases, the thermal effects only give rise to small corrections to the leading terms due to compressibility and viscosity. (C) 1997 Acoustical Society of America.