Annick Pouquet | Laboratory for Atmospheric and Space Physics, CU Boulder, and National Center for Atmospheric Research
Interactions of eddies and waves in rotating stratified turbulence
Analyzing a large data base of high-resolution direct numerical simulations of decaying rotating stratified flows, one can show that anomalous mixing and dissipation, marked anisotropy, and strong intermittency are all observed simultaneously in an intermediate regime in which both waves and eddies interact efficiently nonlinearly. In an intermediate regime, the efficiency of dissipation varies linearly with the control parameter, i.e. the Froude number.
A critical behavior governed by the stratification occurs at Richardson numbers of order unity, close to the shear and convective instability thresholds, and with an accumulation of data points in its vicinity. This confirms the central dynamical role of strong large-scale intermittency in the vertical velocity, the temperature and their gradients in such turbulent flows.