Large Atwood number, miscible-liquid experiments on the Rayleigh-Taylor and Richtmyer-Meshkov instabilities.

Experiments are presented in which an incompressible system of two miscible liquids with a large density difference ($A\approx 0.5)$ is accelerated to produce the Richtmyer-Meshkov (RM) or Rayleigh-Taylor (RT) instabilities. The initially stably stratified liquid combination is contained within a rectangular tank that is accelerated on a vertical rail system. In the RM Experiments the tank is released from the top of the rail system, after which it impacts a spring that introduces the impulsive acceleration and the RM instability develops while the tank is in freefall. In the RT experiments, the same rail system is used; however, instead of impacting a spring the tank is accelerated downward using a weight and pulley system. The resulting fluid flows are observed using backlit photography. The initial perturbations are either forced (by oscillating the tank in the horizontal direction to produce a standing wave) or random (due to molecular motion or background noise). Measurements taken from the data compare well with theory and models for both the RM and RT instabilities.