01. Experimental/Computational Fluid Dynamics

In recent years, the environment surrounding cavitation bubbles has changed significantly. Additionally, the microjets formed during cavitation bubble collapse and the shock waves emitted during rebound have been actively utilized for cleaning, sterilization, and drug delivery. In the scenarios above, the presence of a single bubble at infinity is rare. In many cases, symmetry breaking occurs because of the presence of various boundaries in the vicinity of the bubble, including neighboring bubbles. Studies pertaining to the non-spherical motion of bubbles under various boundary conditions have progressed, and the behavior of bubbles near flat walls, curved walls, free surfaces, and elastic bodies has been clarified. However, most of these behaviors were interpreted as axisymmetric or three-dimensional flows and generally regarded as spherical motions during cavitation bubble growth. Thus, the behavior of two-dimensional (2D) cavitation bubbles remain primarily unknown. Recently, the asymmetric motion of 2D cavitation bubbles has been discussed based on the asymmetric motion of 2D bubbles with respect to the entry of objects into water. In this study, discharge bubbles were generated in a 2D space between two flat plates and then visualized using a high-speed video camera. The translational motion characteristics of the 2D cavitation bubbles under various rigid boundary conditions were investigated. The main results include the relationship among the relative wall distance, the collapse period, and the migration of the bubble for 2D cavitation bubbles located near the flat wall and in the corners.

Kotaro Sato

Prof.