Natural Convection

Natural Convection

In natural convection, when air is taken as the working gas, a very basic fundamental assumption lies beneath it. Whether is it taken as ideal or a real gas? A basic paradox encompasses this assumption. Let’s have a look …..........

When we explain the fundamental of natural convection then we say it occurs due to buoyancy effect by gravity since hotter gases have lower density than the cold ones. Heavier cold gas comes down and lighter hot gas goes up. Thus the whole phenomenon of convection occurs.

And after that when we calculate “Grashoff number” for natural convection that time we assume the air is an ideal gas and use ideal gas equation and calculate beta (volumetric expansion coefficient which comes in Grashoff number formula). And now the question arises….

Food For Thought: - The ideal gas equation comes from the kinetic theory of gases and it has one underlying assumption that “gravity doesn’t have effect of the gas molecules”.

Question:-If you are taking air as an ideal gas, then how natural convection can happen because gravity doesn’t affect the ideal gas?