Single-Phase Natural Convection
This chapter discusses single-phase natural convection phenomena. The term “natural convection” denotes the phenomena characterized by a fluid motion which is due only to heat transmission. In a gravity field, with vertical heating slabs, flow is also possible with low ΔT. Clearly, mechanical energy is available as an effect of the fluid motion; fluid is accelerated up to a velocity such that, under stationary conditions, the buoyancy forces are equal to the friction forces among the fluid currents. The arbitrary nature of the velocity and temperature profiles’ introduction makes this procedure approximate. The integral method consists in the integration of the differential conservation equations, making use of reasonable temperature and velocity profiles, a priori hypothesized. Scale analysis method is very helpful in the resolution of several heat transfer problems, especially pertaining to natural convection, giving the order of magnitude of the physical parameters of interest.