Three-dimensional rayleigh-taylor instability part 2. experiment

Three-dimensional Rayleigh-Taylor instability, induced by accelerating a smallvolume of water down a vertical tube using air pressure, is investigated. Two geometries are studied: a 15.875 em circular tube and a 12.7 em square tube. Runs were made withinitial disturbances in the form of standing waves forced by shaking the test section in a lateral direction. Accelerations ranging from 5 to 10 times gravitational acceleration and wavenumbers from 1 cm^-1 to 8 cm^-1 are studied. The resulting instability was recorded and later analysed using high-speed motion picture photography. Measurements of the growth rate are found to agree well with linear theory. In addition, good qualitative agreement between photographs and threedimensional surface plots of the weakly nonlinear solution of Part 1 of this series (Jacobs & Catton 1988) is obtained.