Power-Law Spectra of Incipient Gas-Curtain Turbulence

We investigate the evolution of a thin curtain of heavy gas (SF6 ) embedded in a lighter gas (air) and accelerated with a Mach 1.2 planar shock wave. The Richtmayer-Meshkov instability leads to growth of the initial perturbations of the curtain and eventually to transition to turbulence. We visualize a time sequence of images of a section of the flow illuminated with a laser sheet. The SF6 is premixed with tracer (glycol fog), so the intensity of the light scattered off the curtain grows with the local density. As the curtain evolves towards a fully mixed state, real-space correlations of the density, inferred from scattered light intensity, show the emergence of a power-law behavior, indicative of transition to turbulence. copyright 1998 The American Physical Society