Abstract:

Strong nonlinearity of bubbly liquids is a most interesting property not only for its theoretical importance in nonlinear acoustics but also for its potential application in, for example, ultrasound imaging technology. A physical model which describes the nonlinear property of liquids containing uniform size bubbles is presented [Ultrasound Med. Biol. 21, 545--552 (1995)]. The theory is successful to some extent but still has some limitations since the sizes of the bubbles are usually not exactly the same. In this paper, a model dealing with more practical situations, i.e., liquids containing many bubbles whose sizes are randomly distributed is extended. The effective nonlinearity parameter B/A (as high as about 10[sup 4]) and attenuation coefficient for these bubbly liquids are given. Calculations and comparisons show that the improved model explains the existent experiments more satisfactorily. [Work supported by the National Science Foundation of China.]