Researchers from the Naval Architecture and Ocean Engineering at Shanghai Jiao Tong University have conducted a refined numerical investigation into the dynamics of shallow-depth underwater explosions. Their work, published in the International Journal of Naval Architecture and Ocean Engineering, offers new insights into the flow-field characteristics of such explosions, with significant implications for naval defense and ocean engineering.
The study, led by Ming He and colleagues, employed a self-developed Eulerian finite element solver to model and analyze the complex physical processes involved in underwater explosions. The research began with the validation of the numerical model against theoretical predictions and small-scale experimental results. The numerical simulations showed good agreement with both theoretical and experimental data, establishing a robust foundation for further investigation.
A key aspect of the study was the incorporation of the cavitation cut-off effect into the underwater explosion model. Cavitation, the formation of vapor cavities in a liquid, significantly influences the dynamics of underwater explosions. The researchers quantitatively analyzed the cavitation phenomenon through flow-field pressure measurements, providing a deeper understanding of its role in these explosive events.
The investigation also explored the dynamic characteristics of the bubble and water hump generated by the explosion under various initial conditions and stand-off parameters. The stand-off parameter, which represents the distance from the explosion to the free surface, was found to play a crucial role in the behavior of the bubble and water hump. The researchers also examined the effect of gravity on these physical processes, contributing to a more comprehensive understanding of the underlying mechanisms.
One of the study’s notable findings was the quantitative analysis of the bubble pulsation period, taking into account the free surface effect. The results were compared with Cole’s experimental formula for underwater explosions. The study revealed that when the stand-off parameter exceeds 2, the influence of the free surface on the empirical period of the bubble becomes insignificant. This finding has important implications for the prediction and mitigation of the effects of shallow-depth underwater explosions.
Overall, the research provides broad insights into shallow-depth underwater explosions from theoretical, experimental, and numerical perspectives. The findings contribute to the ongoing efforts to enhance the safety and security of naval vessels and offshore structures. By refining the understanding of the flow-field characteristics and dynamic processes involved in underwater explosions, this study paves the way for more effective defense strategies and engineering solutions in the maritime sector. Read the original research paper here.