Self-similarity and universality in Rayleigh–Taylor, Boussinesq turbulence

We report and discuss case study simulations of the Rayleigh–Taylor instability in the Boussinesq, incompressible regime developed to turbulence. Our main focus is on a statistical analysis of density and velocity fluctuations inside of the already developed and growing in size mixing zone. Novel observations reported in the article concern self-similarity of the velocity and density fluctuations spectra inside of the mixing zone snapshot, independence of the spectra of the horizontal slice level, and universality showing itself in a virtual independence of the internal structure of the mixing zone, measured in the rescaled spatial units, of the initial interface perturbations.