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Experimental results are presented for steady natural convection in a two-dimensional, partially divided, rectangular enclosure, in which two of the vertical walls were maintained at different uniform temperatures and the top and bottom walls were insulated. The partition plate was adiabatic, and the experiment was carried out both with and without an opening in the partition. Rayleigh numbers ranging from 106 to 108 and opening ratios of 0, 1/8, and 1/4 were investigated for an enclosure aspect ratio (length/height) of 2 and Prandtl number of 7 (for water). Local velocity and temperature measurements were made with a laser-Doppler velocimeter and thermocouple probes. Flow visualization using colored dye was also performed. Results show that there was a recirculation zone in the upper and left quadrant of the enclosure when there was no opening in the partition plate. With an opening in the partition, the recirculation zone was absent and the heat transfer rate increased. An unopened partial obstruction would reduce the heat transfer rate by an amount of 12 to 30 percent depending on the Rayleigh number. However, the opening seems to have little effect on the velocity and temperature profiles of the left-moving fluid on the bottom wall. A correlation of the Nusselt number is derived, which shows that the heat transfer rate increases as the Rayleigh number or opening ratio increases.

Experimental and theoretical results are presented for the flow in a half-filled annulus between horizontal concentric cylinders with the inner one rotating and the outer one at rest. A laser-Doppler velocimeter was used to measure the mean tangential and/or corresponding turbulent velocity distributions for both the laminar and turbulent regimes. Colour dyes were also used to visualize the flow patterns. The Reynolds number based on the gap width varied from 67 to 3242, which corresponds to a Taylor number ranging from 25 to 1200. From the graph of local moment coefficient versus Taylor number and the visualization results, laminar, transition and turbulent regimes are identified. In the analysis, the governing equations are expressed in stream-function and vorticity forms and expanded in terms of the power series of the annulus aspect ratio. The zero- and first-order solutions are then solved numerically. Various features of the flow, in particular the presence of vortices in the exit end region and their absence from the entry end region, predicted in the analysis, are confirmed by the experimental findings.

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