Asymmetric natural convection flow in three dimensional attic space

Natural convection in an attic space with top cooling is investigated by three dimensional numerical simulation for a wide range of Rayleigh numbers. The numerical results show the development of natural convection flow in attic space. Three stages: an initial stage, a transitional stage and a fully developed stage are involved. At higher Rayleigh numbers, the flow in the attic space is three dimensional and asymmetry with respect to geometric symmetry plane. The critical Rayleigh number for asymmetric flow is found.