DEVELOPING CONVECTION ABOVE A FINITE HORIZONTAL SURFACET. Y. Chu DOI: 10.1615/IHTC9.2980 AbstractThe problem described  the initiation of convection above a suddenly heated horizontal surface of finite extent  is of interest to both the engineering and geophysical fields. The apparatus used in the described experiment consisted of an enclosure with a square planform. A heated strip, whose width was equal to onefourth of the length of a side of the enclosure, was centered on the lower inside surface of the enclosure. The top of the fluid layer was maintained at a constant temperature, and the depth of the layer was equal to the width of the heated strip. The flow field, heater surface temperature, and heat flux distribution were studied. Flow was observed to initiate near the edges of the heated strip as two convection cells. In time, the two cell boundaries merged into a central plume rising above the heated strip. The velocity field was found to be the most sensitive indicator of convection; surface temperature, the least. Despite the finite width of the heated strip and the finite depth of the layer, the initiation of convection appeared to readily conform to Howard's model of conduction layer instability developed for infinite layers. The average Rayleigh number for the critical conduction layer was 1120. 

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