Transitional free convection flow and heat transfer within attics in cold climate

The transitional free convection flow and heat transfer within attics in cold climate are investigated using 3-D numerical simulations for a range of Rayleigh numbers from 103 to 106 height-length ratios 0.1 1.5. development process the attic could be classified into three-stages: an initial stage, fully developed stage. Flow structures different stages including transverse longitudinal rolls critically analyzed terms location strength their impacts on transfer. transition unsteady asymmetry stage is discussed fixed ratio 0.5. Various regimes given bifurcation diagram parameter space (102 < Ra 107) (0.1 A 1.5). time series rate through bottom wall quantified ratios. overall low Prandtl fluid (Pr = 0.7) enhanced based structure.