Reynolds stresses and mean fields generated by pure waves: applications to shear flows and convection in a rotating shell - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Journal of Fluid Mechanics Année : 2008

Reynolds stresses and mean fields generated by pure waves: applications to shear flows and convection in a rotating shell

Résumé

A general reformulation of the Reynolds stresses created by two-dimensional waves breaking a translational or a rotational invariance is described. This reformulation emphasizes the importance of a geometrical factor: the slope of the separatrices of the wave flow. Its physical relevance is illustrated by two model systems: waves destabilizing open shear flows; and thermal Rossby waves in spherical shell convection with rotation. In the case of shear-flow waves, a new expression of the Reynolds–Orr amplification mechanism is obtained, and a good understanding of the form of the mean pressure and velocity fields created by weakly nonlinear waves is gained. In the case of thermal Rossby waves, results of a three-dimensional code using no-slip boundary conditions are presented in the nonlinear regime, and compared with those of a two-dimensional quasi-geostrophic model. A semi-quantitative agreement is obtained on the flow amplitudes, but discrepancies are observed concerning the nonlinear frequency shifts. With the quasi-geostrophic model we also revisit a geometrical formula proposed by Zhang to interpret the form of the zonal flow created by the waves, and explore the very low Ekman-number regime. A change in the nature of the wave bifurcation, from supercritical to subcritical, is found.
Fichier non déposé

Dates et versions

hal-03808114 , version 1 (10-10-2022)

Identifiants

Citer

Emmanuel Plaut, Y. Lebranchu, Radostin D. Simitev, F. Busse. Reynolds stresses and mean fields generated by pure waves: applications to shear flows and convection in a rotating shell. Journal of Fluid Mechanics, 2008, 602, pp.303-326. ⟨10.1017/S0022112008000840⟩. ⟨hal-03808114⟩
15 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More