Objective This study investigates the evolution of the interaction between an underwater explosion bubble and the free liquid surface in terms of compressibility and viscous effect.

Methods A numerical model of an underwater explosion bubble coupled with the free liquid surface is developed on the basis of the compressible two-phase flow solver of OpenFOAM and the volume of fluid method (VOF). The validity of the numerical model is then verified by comparison with the experimental results. The effects of different flow field viscosities and distance parameters on the bubble pulsation process and free-surface spike motion are also investigated.

Results The flow field viscosity effect has an important influence on the surface spike height, bubble pulsation period and bubble pulsation, especially the bubble morphology in the rebound phase. Ring bubble morphology is not easy to maintain in low viscosity fluid, so the tearing phenomenon of the bubble can easily occur. As the distance parameter increases, the coupling effect between the free surface and the bubble gradually decreases, the bubble pulsation period increases, the heights of the primary and secondary surface spikes decrease, and the widths of the primary spike and liquid jet gradually increase.

Conclusion The results of this study can provide useful references for determining the evolution mechanism of bubbles under different flow field viscosities.