Yuren Tian
Xiaoyu Zheng
Glynn Holt
Robert E. Apfel
Ctr. for Ultrason. and Sonics, Yale Univ., 2159 Yale Station, New Haven, CT 06520
In a surfactant solution, a gas bubble can be covered by an adsorbed film of surfactant. When the bubble is excited into radial oscillations by a sound field, the surface concentration of the surfactant varies with the surface area and the mass interchange between the surface and the bulk liquid. As a result, the surface tension becomes a function of the bubble radius. Previous theoretical work on this subject [R. E. Glazman, J. Acoust. Soc. Am. 74, 980--986 (1983)] will be commented on and the equations governing the radial oscillations for this kind of gas bubble will be discussed. By numerically solving the equation under different initial bubble sizes, sound pressures, and driving frequencies, one can determine the effects of variable surface tension, surface viscosity, and surface mass transfer on the motions of the gas bubble. Thresholds of transient cavitation will also be estimated by including these effects. [Work supported by NASA through JPL, Contract No. 958722.]