Experiments on the two- and three-layer Rayleigh-Taylor instability

Incompressible Rayleigh-Taylor instability experiments are presented in which two or three stratified miscible liquids having Atwood number of 0.3 at each interface are accelerated in a vertical linear induction motor driven drop tower. A test sled capable of only vertical motion contains the experiment tank and visualization equipment. The sled is positioned at the top of the tower within the linear motors, then is accelerated downward causing the initially stable interface or interfaces to become unstable and allowing the Rayleigh-Taylor instability to develop. Forced initial perturbations are produced by vertically oscillating the test sled prior to the start of acceleration. The experimental tank is illuminated with a white backlight. Video is recorded with a monochromatic high speed video camera allowing for the measurement of mixing layer growth rates for both the single- and two-interface cases.