FLOW PATTERNS OF NATURAL-CONVECTION IN AN AIR-FILLED VERTICAL-CAVITY

Flow patterns of two-dimensional natural convection in a vertical air- filled tall cavity with differentially heated sidewalls are investigat ed. Numerical simulations based on a finite difference method are carr ied out for a wide range of Rayleigh numbers and aspect ratios from th e onset of the steady multicellular flow, through the reverse transiti on to the unicellular pattern, to the unsteady multicellular flow. For aspect ratios (height/width) from 10 to 24, the various cellular stru ctures characterized by the number of secondary cells are clarified fr om the simulations by means of gradually increasing Rayleigh number to 10(6). Unsteady multicellular solutions are found in some region of R ayleigh numbers less than those at which the reverse transition has oc curred. (C) 1998 American Institute of Physics.