Eulerian mean flow from an instability of convective plumes

Authors
Citation
S. Childress, Eulerian mean flow from an instability of convective plumes, CHAOS, 10(1), 2000, pp. 28-38
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
CHAOS
ISSN journal
1054-1500 → ACNP
Volume
10
Issue
1
Year of publication
2000
Pages
28 - 38
Database
ISI
SICI code
1054-1500(200003)10:1<28:EMFFAI>2.0.ZU;2-G
Abstract
The dynamical origin of large-scale flows in systems driven by concentrated Archimedean forces is considered. A two-dimensional model of plumes, such as those observed in thermal convection at large Rayleigh and Prandtl numbe rs, is introduced. From this model, we deduce the onset of mean flow as an instability of a convective state consisting of parallel vertical flow supp orted by buoyancy forces. The form of the linear equation governing the ins tability is derived and two modes of instability are discussed, one of whic h leads to the onset of steady Eulerian mean flow in the system. We are thu s able to link the origin of mean flow precisely to the profiles of the unp erturbed plumes. The form of the nonlinear partial differential equation go verning the Eulerian mean flow, including nonlinear effects, is derived in one special case. The extension to three dimensions is outlined. (C) 2000 A merican Institute of Physics. [S1054-1500(00)01101-0].