Survey of Thermal, Radiation, and Viscous Damping of Pulsating Air Bubbles in Water

A theoretical discussion is presented on the fundamental processes by which pulsating gas bubbles in liquids dissipate their energy. The survey is limited to the case where the amplitude of the volume pulsations are assumed to be sufficiently small that the pulsations may be described by linear equations. A portion of the energy of the bubble system is lost by the radiation of spherical sound waves, a part is lost by heat conduction due to the polytropic compressions and expansions of the enclosed gas, and a portion is lost by viscous dissipation attributed to viscous forces acting at the gas‐liquid interface. A survey is made of the procedures for measuring the resonant damping constant as described in the methods of successive oscillations, width of the resonance response, standing‐wave ratios, and resonance absorption. Experimental results verify that the damping at resonance is due to thermal and radiation, and possibly viscous damping.