Development of a convective instability as wavy rolls in a Poiseuille-Rayleigh-Bénard flow

Hervé Pabiou (1) , Xavier Nicolas (2, 3) , S. Xin (4) , S. Mergui (5)

1 FAST - Fluides, automatique, systèmes thermiques
2 MSME - Laboratoire de Modélisation et Simulation Multi Echelle
3 LETEM - Laboratoire d'Etudes des Transferts d'Energie et de Matière
4 LIMSI - Laboratoire d'Informatique pour la Mécanique et les Sciences de l'Ingénieur
5 FAST - Fluides, automatique, systèmes thermiques

A both experimental and numerical study of a mixed convective flow in a rectangular channel heated at the bottom and cooled at the top is reported. In such configuration, it is well known that for a Rayleigh number above a critical value and for sufficiently high Reynolds number, longitudinal counter-rotating rolls develop. A linear temporal stability analysis conducted in 1991 detected the onset of a wavy instability of the longitudinal rolls. In our study, experimental results and 3D direct simulations clearly show the development of the wavy pattern and point out the convective behaviour of this instability. To the knowledge of the authors, it is the first time that this instability is observed.

Mots clés: 3D numerical simulation; Convective instability; Experimental observation; Mixed convection; Open flow; numerical simulations; Poiseuille-Rayleigh-Bénard; Poiseuille flow; Rayleigh-Bénard

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]; Thermique [physics.class-ph]; Thermique [physics.class-ph]

Hervé Pabiou, Xavier Nicolas, S. Xin, S. Mergui. Development of a convective instability as wavy rolls in a Poiseuille-Rayleigh-Bénard flow. Mechanics & Industry, 2003, 4 (5), pp.537-543. ⟨10.1016/j.mecind.2003.07.016⟩. ⟨hal-00695036⟩