Numerical simulation on the characteristics of underwater two-point explosion shock waves in limited regions based on OpenFOAM

Underwater two-point explosions are commonly encountered in engineering fields such as underwater blasting. The cooperative effects of multiple explosive sources result in more complex shockwave load characteristics compared to single-source underwater explosions. Based on the open-source software OpenFOAM, this paper establishes a multi-physics coupled numerical model for underwater multi-point explosions in a limited water domain with a free surface and a rigid bottom. Numerical investigations are conducted on the complex evolution of shockwave loads generated by multiple underwater explosive sources under different spatial distributions and initiation sequences. It is found that the spacing between explosive sources and the initiation phase difference are key parameters governing shockwave superposition. Variations in the spacing between two explosive sources have little effect on the pressure fields on the left and right sides along the horizontal direction of the two-source system, but significantly influence the pressure field in the region perpendicular to the line connecting the centers of the two sources. Within a certain range, a larger initiation spacing can increase the positive pressure duration of the shockwave. Delayed initiation with a certain time interval can significantly enhance the peak overpressure of the initial superimposed wave. A noticeable pressure truncation phenomenon occurs near the free surface, while multiple reflections and superposition of shockwaves in the rigid bottom boundary region significantly increase the nearby pressure field, producing a reflected wave enhancement effect.