Multipole resonances in sound scattering from gas bubbles in a liquid

Abstract

The acoustic scattering properties of spherical gas bubbles in a liquid differ from those of a pressure-release sphere by the well-known ’’giant’’ monopole resonance at very low frequencies, which is due to the compressibility of the gas contained in the bubble. We show here that, in addition to this monopole resonance, a large number of higher-frequency resonances exist which are either overtones of the monopole, or which correspond to both fundamental and overtones of bubble vibrations of higher multipolarity. Although much smaller in size than the giant monopole, these resonances may nevertheless constitute features of some importance in sound scattering from gas bubbles.