Numerical study on the mitigation effect of water in the immediate vicinity of a high explosive on the blast wave

This paper investigates explosions in a straight square tube in order to understand the mitigation effect of water on blast waves that emerge outside. Numerical simulations are used to assess the effect of water that is filled inside the tube. The water reduces the peak overpressure at the tube exit and outside, which agrees well with the experimental data. The increases in the kinetic and internal energies of the water are estimated, and the internal energy transfer at the air/water interface is shown to be an important factor in mitigating the blast wave on the ground in the present numerical method. Two mechanisms of the energy transfer are proposed in the present study. Initially, the strong shock wave reflects off and transmits water. A high-energy transfer into the water from air is promoted by the shock compression of water. Subsequently, as the shock wave propagates along the water surface, the air is adiabatically compressed continuously, and the pressure and temperature differences between the shocked-air and water induce a more gradual transfer of internal energy into the water.