ASA 125th Meeting Ottawa 1993 May

4pPA7. The radial oscillations of a gas bubble in a surfactant solution.

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.]