NUMERICAL EXPERIMENTS ON LAMINAR NATURAL-CONVECTION IN RECTANGULAR CAVITIES WITH AND WITHOUT HONEYCOMB-STRUCTURES

Two-dimensional finite difference calculations are carried out to stud y laminar flow in longitudinal and transverse convection rolls for thr ee different geometries: a single rectangular cavity with high aspect ratio; a double cavity with a thin separation sheet; and a double cavi ty with a separation sheet and a honeycomb structure. The equations fo r the convection-diffusion in the fluid and conduction in the solid re gion are solved simultaneously. Good agreement with experimental data is achieved for Rayleigh numbers not too high above the critical value for the onset of secondary convection rolls (Ra < 8500 for vertical a nd Ra < 2700 for horizontal cavities filled with air). Simulation fail s for inclined cavities, where the flow structure is essentially three -dimensional.