The dynamic behavior of a gas bubble near a wall

In this paper, a numerical model based on the potential flow theory is established to simulate the interaction of a gas bubble with a nearby wall. The time-integration boundary integral method is used to solve the dynamics of a gas bubble. With this method the numerical calculations show an excellent agreement with the experimental data. Employing the numerical code based on the presented algorithm, the dynamics of a gas bubble close to a rigid wall is investigated systematically, especially the relationship between various characteristic parameters and the Bjerknes effect due to the presence of a nearby wall. It is found that Blake's criterion, which is usually used to predict the direction of the bubble jet, has a great degree of accuracy for the bubble relatively far away from the wall and bubble near a wall, there is a significant error, attributed to its simplifications and assumptions. Further studies show that an oblique jet will be formed when a bubble close to an inclined wall collapses, direction and width of which have a close relationship with the characteristic parameters used to characterize the bubble. For the bubble near a horizontal wall, a liquid jet pointing directly to the wall is developed generally when the Bjerknes attraction and buoyancy are in the same direction; and at the same time, if the Bjerknes attraction is in the opposite direction of buoyancy, the direction of the jet will depend on a criterion. Then the interaction of gas bubble between complicated walls of some a submarine is also studied, which shows the most dangerous induced loading condition of structure in water, and the evidently effects of bubble jet on loading. The special phenomena mentioned above have a great significance for the further study on the interaction of the bubble with its boundaries.