Étude numérique du couplage de la convection naturelle avec le rayonnement de surfaces en cavité carrée remplie d'air

Abstract

A numerical tool is developed for coupling natural convection in cavities with surface radiation and computations are performed for an air-filled square cavity whose four walls have the same emissivity. Compared to the adiabatic case without radiation, the top wall is cooled, the bottom wall is heated, air flow along the horizontal walls are reinforced and thermal stratification in cavity core is reduced. Detailed analysis shows that net radiative heat flux is linear with Δ T if Δ T ≪ T 0 , which is the case at low Rayleigh number, and that radiative Nusselt number is a linear function of the cavity height. Surface radiation induces an early transition to time-dependent flows: for ɛ = 0.2 and a cavity height of 0.335 m the critical Rayleigh number is equal to 9.3 × 10 6 and the corresponding Hopf bifurcation is supercritical. Furthermore, multiple periodic solutions are observed between Ra = 1.2 × 10 7 and 1.3 × 10 7 . To cite this article: H. Wang et al., C. R. Mecanique 334 (2006).