Interactions between two oscillating bubbles in a rigid tube

The interaction phenomena between two oscillating vapor bubbles in a rigid narrow tube is studied using a high-speed video camera. The bubbles are generated by low-voltage electric sparks in water held by glass tubes of various inner diameters (6 mm, 8 mm and 10 mm). The bubbles not only deform greatly during the first oscillation period, but also induce a liquid flow in various directions after their collapse. The interaction phenomena are summarized in two aspects: four kinds of deformation interactions and three different directions of the post-collapse flow. Moreover, the key factors affecting the interaction are discussed in detail. It is found that the deformation phenomena are mostly dependent on the phase difference. The threshold of the blocking effect is also discussed, which has a significant influence on the post-collapse flow's direction. In order to identify the cases of stagnation, a simple momentum model is presented.