[Back]

R. Mettin, Ch. Lechner, M. Kauer, M. Koch, C. Cairos Barreto, W. Lauterborn:
"Avalanche collapse of bubbles in holes";
Talk: Drittes Kolloquium Kavitation und Kavitationserosion, Bochum; 2018-11-06 - 2018-11-07.

Acoustic cavitation is the long known agent of ultrasonic cleaning. It is well suited for the removal
of contaminations from complex surface features like recesses, grooves, holes or channels that are
otherwise difficult to reach. However, the detailed dynamics of cavitation bubbles in such
constricted geometries has not been fully explored. Recent investigations in the context of surface
plating and enhancement of mass transfer by cavitation have shown partly involved bubble
behaviour in blind and through holes [Kauer et al., 2018]. A peculiar phenomenon occurs for
bubbles that reach the hole or channel diameter during expansion: Several such bubbles can expand
simultaneous situated in a row and forming a plug-flow situation in the channel. The subsequent
collapse happens in an avalanche-like manner from the hole entrance to the inner centre or end.
Preliminary evaluation of the dynamics suggests a shock-wave mediated collapse chain of the
bubbles. Further analysis and numerical simulations are presented here. Of particular interest is the
question whether high pressure loads on the solid structures and potential of damage occur due to
the avalanche collapse.