The Richtmyer-Meshkov instability (RMI) on a liquid-gas interface has attracted much attention but remains a challenge due to the uncertain effects of surface tension and viscosity on its behaviour. In this study, experiments on the evolution of a shocked two-dimensional water-air interface were first conducted in a drop tower apparatus. The impulsive acceleration was generated by dropping a water tank onto coil springs, resulting in a maximum acceleration of 195 times the gravity acceleration. Subsequently, the behaviours of bubbles and spikes under high-Atwood-number conditions were examined. Two distinct models for quantifying the effects of surface tension and viscosity on RMI were compared against the experimental results. It was revealed that the bubble development is dominated by RMI, while the spike behaviour is primarily initiated by flow focusing, followed by RMI. Later, an analytical model was established to quantify the hydrodynamic instabilities by considering surface tension, viscosity, and flow focusing. Finally, a comparison was made regarding the contributions of various mechanisms to the instability development of a water-air interface triggered by an impact.

hydrodynamic instability,Richtmyer-Meshkov instability,multi-phase flow