Experimental investigation of the miscible, two-dimensional, incompressible liquid Rayleigh-Taylor and Richtmyer-Meshkov instabilities for large Atwood numbers

Experiments are presented in which an incompressible system of two miscible liquids with a large density difference (Atwood number ≈ 0.5) is accelerated to produce the Richtmyer-Meshkov (RM) or Rayleigh-Taylor (RT) instabilities. The initially stable 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 primarily observed using backlit imaging. 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. Also, new visualization techniques were tested in attempts to compensate for the lack of refractive index matching between the two fluids.