Dissipative effects on Bjerknes forces between two bubbles

The time-averaged forces exerted by a sound field between two gas bubbles, normally called Bjerknes forces, are examined. The surrounding medium is assumed to be an incompressible viscous liquid. It is shown that the acoustic streaming, which develops around the bubbles due to viscosity, adds one more term to the Bjerknes force that is dominant when the viscous wavelength is large compared with the bubble radii. (C) 1997 Acoustical Society of America.