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In a companion paper, a reduced model for propagation of acoustic waves in acloud of inertial cavitation bubbles was proposed. The wave attenuation wascalculated directly from the energy dissipated by a single bubble, the latterbeing estimated directly from the fully nonlinear radial dynamics. The use ofthis model in a mono-dimensional configuration has shown that the attenuationnear the vibrating emitter was much higher than predictions obtained fromlinear theory, and that this strong attenuation creates a large traveling wavecontribution, even for closed domain where standing waves are normallyexpected. In this paper, we show that, owing to the appearance of travelingwaves, the primary Bjerknes force near the emitter becomes very large and tendsto expel the bubbles up to a stagnation point. Two-dimensional axi-symmetriccomputations of the acoustic field created by a large area immersed sonotrodeare also performed, and the paths of the bubbles in the resulting Bjerknesforce field are sketched. Cone bubble structures are recovered and comparereasonably well to reported experimental results. The underlying mechanismsyielding such structures is examined, and it is found that the conicalstructure is generic and results from the appearance a sound velocity gradientalong the transducer area. Finally, a more complex system, similar to anultrasonic bath, in which the sound field results from the flexural vibrationsof a thin plate, is also simulated. The calculated bubble paths reveal theappearance of other commonly observed structures in such configurations, suchas streamers and flare structures.

A simple model of ultrasound propagation in a cavitating liquid. Part II: Primary Bjerknes force and bubble structures