Predicting the collapse direction of large-scale pulsating bubbles based on Kelvin impulse theory

Predicting the collapse direction of large-scale pulsating bubbles is crucial for evaluating the safety performance of marine vessels in ocean applications involving underwater explosions and high-pressure bubble detection. This study develops a rapid forecasting method for large-scale pulsating bubbles under the influence of hybrid boundaries (free surface, bottom, and sidewall) based on the Kelvin impulse theory. The boundary element method was used to simulate bubble jets and clarify the applicability of the analytical solution in predicting the direction of large-scale bubbles. The analytical solution of the Kelvin impulse underestimates the buoyancy effects of bubbles near the bottom. However, near the free surface, the strong interaction between the bubble and free surface strengthens the downward movement of the bubble, resulting in an analytical solution with improved accuracy. A buoyancy correction factor was introduced to rectify inaccuracies in the analytical solution near the bottom. The correction factor was obtained under the condition of a vertically neutral collapse for the bubbles. Comparison of the simulation results with theoretical values across various buoyancy parameters indicate that the modified analytical solution can effectively predict the direction of bubble collapse across most parameter domains. The modification method for analytical solution proposed in this study may serve as a reference for practical operations aimed at protecting marine vessels near underwater explosions or marine seismic sources.