Acoustic streaming near Albunex spheres

Acoustic streaming near bubbles in an external standing-wave sound field has been an interesting research topic for decades. It was relatively difficult to visualize the acoustic streaming pattern experimentally, especially for small bubbles due to the instability of the bubbles and difficulties associated with the optical technique. Using Albunex spheres (a contrast agent for ultrasonic imaging), a specially designed microscope device, and a video peak store technique, several acoustic streaming patterns around a single and a pair of Albunex spheres of tens of micrometers radius in a 160-kHz ultrasonic standing wave field have been recorded. Spatial peak pressure amplitude of the standing wave was estimated to be in the order of 0.5 MPa by using optical interferometry. The acoustic streaming velocity was in the range of 50–100 μ/s.