SUMMARY

This work is on investigating coupled buoyancy-driven (Rayleigh-Taylor) and shear-driven (Kelvin-Helmholtz) instabilities using statistically stationary experiments. Employing diagnostics like particle image velocimetry (PIV) and laser induced fluorescence (LIF) in gas tunnels, we make velocity-density field measurements in order to study how dynamics and mixing are linked in variable density flows. In addition to extracting quantities of statistical importance from our measurements (like density-velocity correlations), we also look at how different forces (for example buoyancy and shear) fundamentally drive variable density mixing process (using nondimensional parameters like Richardson number), and how such a mixing process reaches an asymptotic state (using the concept of mixing efficiency). These experiments are of immense significance for atmospheric and oceanic sciences, and variable density turbulence modeling.