Acoustic radiation pressure exerted by a spherical wave on a bubble in a viscous liquid

The paper considers a time-averaged force, which is usually called the acoustic radiation pressure, exerted by a diverging spherical sound wave on a gas bubble in a viscous liquid. The purpose of this study is to investigate viscous effects on the radiation pressure. Within the limit of long sound wavelength two inverse cases are considered. In the first of these, the viscous effects are assumed to be weak such that the bubble radius is much larger than the viscous wavelengths both outside and inside the bubble. In the second case, the viscous effects are assumed to be strong, so that the bubble radius is much smaller than the above viscous wavelengths. It is shown that the expression for the radiation pressure in the latter case becomes drastically different from that in the former case.