| Description |
The radiation force on small rigid particles in a fluid suspension is derived in detail. The foundations of nonlinear acoustics is explored as it relates to the theory of radiation pressure. In the second-order effect of the scattering of sound by sound, it is found that sources of slightly different frequencies interact to produce forces of predetermined direction. Similarly, compressible bodies excited by primary radiation sources may oscillate in a resonant mode and thus produce strong sound waves that scatter off the incident radiation pressure waves. The radiation force on compressible spheres was derived by Crum in a manner that bypasses the scattering of sound by suspended compressible particles and has been extended by ter Haar and Wyard to describe the forces on biological particles in ultrasonic fields. A technique for the manipulation and separation of suspended particles in a fluid medium has been proposed by the author in collaboration with Steve Petersen. Further applications of radiation pressure that are presently employed are discussed and novel uses of acoustic manipulation of particles are suggested. |
