ISSN Online: 2377-424X
ISBN Print: 0-89116-559-2
International Heat Transfer Conference 8
SELECTION OF 2-D PATTERNS NEAR THE THRESHOLD OF THE RAYLEIGH-BENARD CONVECTION
Resumo
Bidimensional steady flows in Rayleigh-Benard convection are obtained by numerical simulation using Chebyshev spectral methods. Our results clearly show the non-uniqueness of stable solutions for the steady Navier-Stokes equations, solved in large cavities (aspect ratio = 6 or 15) Each solution is characterized by its wavenumber at the cavity center. For a given Rayleigh number, the band-width of the allowed wavenumbers is narrower than in the non-confined geometry and plainly depends on the thermal boundary conditions at the lateral walls. However this 2-D mechanism for pattern selection is not sufficient to recover the experimentally observed effect of the wavenumber decrease. Finally 3-D simulations show the necessity of a third componant in order to recover this experimental behaviour.