Experimental investigation of late time Rayleigh---Taylor mixing at high Atwood number

Dynamics of late time, high Reynolds number (Re \textgreater 20000) Rayleigh--Taylor (RT) mixing is studied using statistically steady experiments performed in a multi-layer gas tunnel. The density ratio of air and air-Helium mixture used in the present experiment results in an Atwood number \textasciitilde 0.73. Three types of diagnostics --- back-lit visualization, hot-wire anemometry and stereo particle image velocimetry (S-PIV) --- are employed to obtain mixing width, velocity and density fields, with S-PIV employed for the first time for such experimental conditions. Velocity and density statistics, and their correlations (\textit{u', v', w', }$\rho ', \rho 'v')$ are presented. Calculations of probability density functions (p.d.f.s) and energy spectra are made to provide further insight into the flow physics. Energy budget of the flow is also discussed. \underline {Reference:} AKULA, B. {\&} RANJAN, D. 2016 Dynamics of buoyancy-driven flows at moderately high Atwood numbers. \textit{Journal of Fluid Mechanics 795, 313--355.}