Natural Convection

Convection is the study of conduction in a fluid as enhanced by its "convective transport", that is, its velocity with respect to a solid surface. It thus combines the energy equation, or first law of thermodynamics, with the continuity and momentum relations of fluid mechanics.

In natural convection fluid motion is due solely to local buoyancy differences caused by the presence of the hot or cold body surface. Most fluids near a hot wall, for example, will have their densitiy decreased, and an upward near-wall motion will be induced. Natural convection velocities are relatively gentle and the resultant wall heat flux will generally be less than in forced motion.