High Rayleigh numbers

Convection in a cavity subjected to a large temperature difference and hence a high Rayleigh number is discussed in the present section.  The shadowgraph images were quite clear in these experiments and have been included for comparison. In each of the experiments, a true steady state was not attained even after the passage of a long period of time. Secondly, interferograms were subjected to large refraction errors. The cavity viewed through the schlieren and shadowgraph layouts looked deformed once again due to refraction. Hence, the present discussion is purely descriptive and quantitative data has not been reported. Rayleigh numbers considered are .

Figure 5.22 shows representative images of the convective field recorded after the passage of 8-9 hours of real time.

Figure 5.22: Interferograms, schlieren and shadowgraph images for the higher range of Rayleigh numbers in air.