Dynamics of cavitation bubbles inside a small corner

Cavitation is a ubiquitous phenomenon in nature and bubble dynamics in open spaces have been widely studied, but the effects of the wall on the dynamics of cavitation bubbles in confined spaces are still unclear. Here, the dynamics of cavitation bubbles in small corners is studied experimentally, focusing on the interaction of the bubble with the wall. High-speed photography is used to visualize the temporal development of laser-induced cavitation bubbles in a small corner formed by two rigid walls, and the bubble spreading on the corner walls and the bubble migration is analyzed via digital image processing. We identify three distinct modes of bubble collapse, namely, collapse dominated by annular shrinkage, collapse dominated by wall attraction, and collapse governed by a combination of both annular shrinkage and wall attraction. The distribution of different collapse modes at different opening angles of the corner is also analyzed. The displacement and shrinkage of different parts of the bubble surface, as well as the direction and amount of bubble migration, are determined. The results show that the asymmetric structure of the corner leads to asymmetric bubble dynamics, including asymmetric bubble expansion, spreading, contraction, and migration.