Bifurcations and multiple solutions in a differentially heated cubic cavity
Bifurcations et solutions multiples en cavité 3D différentiellement chauffée
Résumé
In this paper, a differentially heated square/cubic cavity is studied by performing three-dimensional direct numerical simulations. The first bifurcation observed at Ra ≈ 3.2 × 107 is due to the 3D vortex structures generated at the end regions of vertical boundary layers near the median plane. The main results of this Note are that the flow returns to a steady state for higher values of the Rayleigh number R a (7 × 107 and 108 for example) still exhibiting these 3D vortex structures, and that multiple steady flows which differ by their symmetry properties, are obtained for Ra = 10 8. However, the flow reverts to unsteadiness for Ra = 3 × 108. In this latter case, the instability is due to the vertical boundary layers.