Résumé

Abstract

The stably stratified boundary layer was early recognized as a fluid-mechanics problem of fundamental interest. Nonetheless, the study of stratified turbulence and the stable boundary layer have taken different paths: Stratified turbulence is mostly studied as a canonical-flow problem in fluid mechanical engineering. On the contrary, the stably stratified boundary layer is commonly investigated as a parameterization problem—motivated by the need for a working turbulence closure in general circulation and numerical weather prediction models. This gave rise to a number of fixes in turbulence closures which are motivated from a large-scale point of view. Still recently, a lack of fundamental understanding in stratified turbulence is identified as a pertinent challenge in understanding the boundary layer. These two paths are consolidated here applying systematically the direct numerical simulation of a turbulent flow, a tool widely used in fluid mechanical engineering, to study the stably stratified boundary layer.