Shock Processes in Water: Multi-Scale Comparison and Experimental Results

Water as the most common fluid on earth has extraordinary properties. The understanding of the dynamic response of water is important to planetary physics, biology and medicine. Inspired by the relationship between shockwave thicknesses and the intensity of property changes between pre-shock and post-shock states in gas medium, it is interesting to study the response of a liquid medium within shock process, such as liquid argon or water, from numerical and experimental methods, especially from different scales of simulations (continuum and molecular dynamics).Molecular Dynamics (MD) simulations of Hugoniot hydrostatic compression and shockwave propagation processes are performed via Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) within liquid argon and water. 3-sites and 4-sites water topology models with corresponding long-range force solvers are validated under shock conditions and results are compared with literatures. 3-sites flexible water topology model is utilized in a water ensemble consisting of 20x20x240 lattices to establish the Lagrangian shockwave propagation process. The result of shock propagation process indicates that pair potential dominates the total potential energy during shock process and shockwave thickness in water is around 7 nm for a corresponding shockwave velocity 3.2 km/s.A series of three shots of planar-plate impact experiments were conducted at muzzle speed 220.5m/s, 343.9 m/s and 441.5 m/s. The corresponding shockwave velocities in water are 2151.3 m/s, 2382.1 m/s and 2550.6 m/s calculated from the timing of the spectrograms of photon doppler velocimetry (PDV) signals, which are compared with literatures. KO 1-D hydrocode and 2-D iSALE shock physics hydrocode are also implemented to assist PDV spectrogram analysis. This work implements both methods of experiment and computational simulation at multiple scales to interpret the shockwave propagation process within water in a Lagrangian reference frame. The MD simulation provides a method to estimate the shockwave thickness in water