LEGI - UMR 5519
Laboratoire des Ecoulements Géophysiques et Industriels


Université de Grenoble Alpes


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Accueil du site > Actualités > Séminaires > Séminaires 2011 > Mardi 3 mai 2011 à 11h00, salle A103 LEGI

Mardi 3 mai 2011 à 11h00, salle A103 LEGI

Jeff Carpenter (Aquatic Physics Group EAWAG, Swiss Federal Institute of Aquatic Science and Technology)

Titre/Title : A new look at shear instability in density-stratified geophysical flows

Contact : Jan-Bert Flor (EReS)

Résumé/Abstract : The traditional approach to assessing shear-driven instability and mixing in density-stratified geophysical flows is to appeal to the Kelvin-Helmholtz mode of instability. This involves the generation of turbulence and mixing when the destabilizing shear overwhelms the stabilizing influence of the density stratification, and is a common conceptual basis for turbulence and mixing parameterizations. However, this is a simplified view that does not consider alternate modes of instability and mixing in which the density stratification acts as a destabilizing influence on the flow. One such mode - the Holmboe mode - leads to the generation of internal waves that may cause turbulence and mixing through a fundamentally different process. The unique mixing behaviour, evolution of the wave field, and identification of Holmboe waves in a highly-stratified estuary are all described through the combined use of numerical simulations, laboratory experiments, field observations and analytical methods.