...) in the profile as the Rayleigh number changes from 1750 to 1760 indicates the onset of buoyancy-driven convection in the cavity open at the top with aspect ratio of one. This further points toward the possibility of the existence of a critical Rayleigh number in this narrow range of Ra c  = 1750–1760...

...D. Y. Tzou Instability of natural convection in nanofluids is investigated in this work. As a result of Brownian motion and thermophoresis of nanoparticles, the critical Rayleigh number is shown to be much lower, by one to two orders of magnitude, as compared to that for regular fluids. The highly...