Self-sustained oscillations in variable-density round jets

Abstract : The stability properties of round variable-density low-Mach-number jets are studied by means of direct numerical simulation (DNS) and linear stability analysis. Fully three-dimensional DNS of variable-density jets, with and without gravity, demonstrate that the presence of buoyancy causes a more abrupt transition to turbulence. This effect helps to explain differences between normal gravity and microgravity jet diffusion flames observed in the laboratory. The complete spectrum of spatial eigenmodes of the linearized low-Mach-number equations is calculated using a global matrix method. Also, an analytic form for the continuous portion of this spectrum is derived, and used to verify the numerical method. The absolute instability of variable-density jets is confirmed using Brigg's method, and a comprehensive parametric study of the strength and frequency of this instability is performed. Effects of Reynolds number, the density ratio of ambient-to-jet fluid (S1), shear-layer thickness and Froude number are considered. Finally, a region of local absolute instability is shown to exist in the near field of the jet by applying linear stability analysis to mean profiles measured from DNS. © Cambridge University Press 2007.
Type de document :
Article dans une revue
Journal of Fluid Mechanics, Cambridge University Press (CUP), 2007, 582 (july), pp.341-376. 〈10.1017/s0022112007005903〉
Liste complète des métadonnées

Littérature citée [31 références]  Voir  Masquer  Télécharger
Contributeur : Denis Roura <>
Soumis le : dimanche 20 juillet 2014 - 18:43:08
Dernière modification le : jeudi 7 février 2019 - 16:58:44
Document(s) archivé(s) le : jeudi 20 novembre 2014 - 18:15:57


Fichiers éditeurs autorisés sur une archive ouverte




J.W. Nichols, Peter Schmid, J.J. Riley. Self-sustained oscillations in variable-density round jets. Journal of Fluid Mechanics, Cambridge University Press (CUP), 2007, 582 (july), pp.341-376. 〈10.1017/s0022112007005903〉. 〈hal-01023338〉



Consultations de la notice


Téléchargements de fichiers