Heat transfer and boundary layer analyses of laminar and turbulent natural convection in a cubical cavity with differently heated opposed walls

摘要

The buoyancy-driven flow in a cubical cavity with differently heated opposed walls has been chosen to investigate the laminar and turbulent heat transfer in enclosed domains. This type of configuration contains the essential physics existing in flows where transport between a fluid and an adjacent solid surface is controlled by the existence of boundary layers. The dependence of the wall heat transfer on the buoyancy force over the range Ra = 10~5 to Ra = 5.4 × 10~8 has been investigated, for air (Pr = 0.7), using Direct Numerical Simulations. Under the assumption of mixed convection flow within the boundary layer produced by the combined effect of buoyancy and forced convection due to the large-scale flow, we assessed the validity of classical 2D boundary layer solutions in this flow configuration. The resulting characterization of the near-wall flow allows to derive new semi-analytical models for wall transfer applications in enclosed cavities.