Fri July 14th 2017
11:00 – 12:00
ZH286 		Seminar Instabilities and turbulence in a Stratified Environment
Sutanu Sarkar

Details:

We will discuss two examples of turbulence in a stratified environment. The oceanic example concerns tidal flow over rough topography in the deep. Turbulence from the nonlinear breakdown of internal waves generated at the rough topography is essential to maintain the observed stratification in the abyssal ocean and also strongly impacts the biogeochemical state of the ocean. We have performed highresolution DND & LES of tidally forced flow over different types of two-dimensional
obstacles. We will report on the dependence of the spatial and temporal distribution of turbulence on the obstacle geometry and environmental parameters. The atmospheric example concerns the stratified Ekman layer that results when a cooling flux is applied to the ground. DNS shows that different regimes are possible: collapse of turbulence during an initial transient, episodes of temporal collapse and rebirth, a turbulent state that is continuous in time but spatially intermittent and a non-turbulent flow. The conditions that govern the emergence of a specific regime are elucidated using analysis and supporting DNS.
Go back to the agenda.