The focusing effect of shock wave generated by underwater spark discharge in relatively long gaps using elliptical reflector

Underwater pulsed spark discharge (UPSD) shock wave focusing is widely used in marine exploration and lithotripsy. However, research on partial elliptical reflectors within restricted space remains limited. This study developed a fluid–structure interaction model using multi-material arbitrary Lagrangian–Eulerian that had been experimentally validated, substituting the arc expansion process generated by spark discharge with an explosive detonation. We compared the effects of spherical and cylindrical explosion sources with different aspect ratios on shock wave propagation, focusing gain, and energy transmission. We analyzed the axial and radial shock wave behaviors of cylindrical explosion sources and assessed their energy conversion efficiency. The results showed that spherical explosion sources had the highest energy conversion efficiency, whereas the transfer efficiency of cylindrical explosion sources decreased with increasing aspect ratios. The paper concludes with an explanation of the directional characteristics of energy propagation from cylindrical explosive sources based on observed energy change trends in water and the elliptical focusing reflector.