Acoustics 08 Paris 2287 A general theoretical approach to the development of zero-thickness shell models for contrast agent microbubbles, which allows the testing of different rheological laws for encapsulation, is proposed. Based on available experimental data, analysis of the rheological behavior of a lipid shell is made. The problems of existing shell models, such as the dependence of shell parameters on the initial bubble radius and the "compression-only" behavior, are discussed and new

more »

... retical models for their simulation are offered. In particular, it is shown that the inclusion of nonlinear shell viscosity allows one to model the "compression-only" behavior. It is also very important to select an appropriate rheological law describing the dependence of the shell viscosity on the shear rate. A correct choice can reduce considerably the spread of the experimentally estimated values of the shell parameters and eliminate their unnatural dependence on the initial bubble radius.