The similarities and differences between the bubble collapse near a solid wall and in free water

In the actual working condition, the cavitation phenomenon is inevitably accompanied by the collapse of a large number of bubbles, and will affect the performance of hydraulic machinery. Therefore, it is of great significance to study the process of multi-bubble collapse. The double bubble system is the most simplified one in multi-bubble system, and it is also the basis of studying multi-bubble. However, the existing bubble dynamic studies mainly focused on single bubble and its interaction with the wall. This paper studies the interaction between two bubbles with different sizes and the influence of the wall on the process of bubble collapse by the VOF method. We have already investigated the interaction between two bubbles with different sizes without a wall (in free water) in our previous study. In this paper, we find that if there is a wall nearby, these two bubbles move close to each other when collapsing, and both move close to the wall at the same time. Through the study of bubble collapse time in the single bubble and the double bubble system, we find that the existence of the wall will delay the collapse time of bubble. However, the existence of the wall can also increase the intensity of collapse and rebound process of the bubble. Through the study of the center displacement of the bubble, we find that the double bubble system can increase the displacement of both bubbles. The method used in this paper can be easily extended to the study of multi-bubble, which provides a feasible method for the simulation of multi-bubble collapse near the wall. (C) 2020 Elsevier Masson SAS. All rights reserved.