Microstreaming patterns induced by shape modes of acoustically trapped bubbles
* Presenting author
The combination of volumic, translational and nonspherical bubble oscillations induce a relatively slow mean flow, called microstreaming, in the vicinity of the bubble. It is well known that microstreaming and its resulting shear stresses play an important role in medical applications such as sonoporation (permeabilization of a cell membrane). The exact mechanisms are however not fully understood. Only few studies have tried to correlate the relatively slow streaming to the fast temporal bubble dynamics. In the present work, we visualize for the first time microstreaming around an acoustically trapped bubble that is oscillating with axisymmetric shape modes. Different types of streaming patterns can be observed. Correlation to the temporal bubble dynamics allows us to identify several important parameters that define the patterns of microstreaming. As might be expected the mode number plays an important role, nevertheless it is not sufficient to define a streaming pattern. Phase differences between several modal components as well as the bubble size with respect to the resonance frequency have to be taken into account as well.