Stratified shear turbulence: Evolution and statistics

The highest-resolution 3D direct numerical simulations to date of Kelvin-Helmholtz instability are reported. The ensuing turbulence spans a broad range of spatial scales and exhibits Kolmogorov spectra in horizontal planes. Non-Gaussian statistics are observed, with highly intermittent entrainment zones at the edges of the resulting shear layer. Profiles of the local gradient-Richardson number are presented and shown to remain less than 1/4 throughout the entire evolution of the turbulence.