Convection In Differentially Heated Superposed Air-Water Layers

Convection in a differentially heated two-layer system consisting of air and water has been studied experimentally using laser-interferometry. The cavity used for flow visualization is square in cross-section and rectangular in plan having dimensions of 447x32. 1x32.1 mm(3). Experiments with the cavity (half-filled with water, the rest being air) are reported here. The following temperature differences have been imposed across the hot and the cold walls of the superposed layers: (i) DeltaT=10 K, (ii) DeltaT=15 K, and (iii) DeltaT=18 K. The present study is aimed at understanding the following issues: (a) the influence of Rayleigh number on the steady thermal field, and (b) flow coupling mechanisms between the layers. The present investigations show that the thermal field in the fluid layers is primarily determined by the temperature difference and hence the Rayleigh number. Further, the two-layers are thermally coupled at a lower Rayleigh number, while the mechanical and,thermal coupling both become significant at higher Rayleigh numbers.