Dynamics of Rayleigh-Taylor instability in self-similar regime

Rayleigh-Taylor (RT) instability presents itself in a variety of phenomena. Most of these applications involve complex physics and vary dramatically in length and time scales. In this work, results from statistically steady RT experiments are presented that were performed in the convective-type two-layer gas tunnel facility at the Georgia Institute of Technology, using air as heavier fluid and air-helium mixture as lighter fluid. Data is collected at a moderately high Atwood number (~ 0.7) and high mixing Reynolds number (> 20000). Velocity profiles and Reynolds stress profiles are displayed across the mixing layer. To understand the self-similar nature of this flow, collapse in turbulent quantities is examined with appropriate scaling factors, and characteristics such as self-similar mixing growth rate are computed. Calculations of probability density functions and energy spectra are made to further characterize the flow. Experiments like this provide modeling community with large data set of relevant turbulence statistics and explain the nature of turbulence in anisotropic, inhomogeneous flows.