UWFDM-1159 Richtmyer-Meshkov Instability of an Interface Prepared by Removal of a Sinusoidal Plate

Shock tube experiments for the study of the Richtmyer-Meshkov instability are presented. The shock tube is vertical with a square inner cross section. Two new techniques are used to prepare the interface and to determine its initial shape, prior to shock-acceleration. The interface is prepared by retracting a sinusoidally shaped plate initially separating CO2 from air at atmospheric pressure. The gases are arranged with the heavy gas above the plate and, as the plate is retracted, the Rayleigh-Taylor instability commences, causing the initial sinusoidal amplitude to grow. At later times, the interface develops into the mushroom shapes typical of the onset of the KelvinHelmoltz instability. The interface is accelerated by a shock while its shape is still sinusoidal but its amplitude/wavelength ratio is large enough to study the post-shock evolution in the non-linear regime. Planar Mie scattering is used to image the pre-shock evolution of the interface (using a CW Ar laser) and to capture one picture of the shocked interface (using a pulsed Nd:YAG laser). The growth rates of the perturbation amplitude are reported and compared with those predicted by some of the most recent non-linear analytical descriptions of the RM instability.