ABSTRACT
This chapter discusses the important attributes of free convection boundary layers on flat surfaces. In free or natural convection, the macroscopic fluid motion is due to body forces and their dependence on fluid density, which itself is sensitive to temperature and/or concentration of the species that constitute the fluid. The free convection boundary layer is laminar near the leading edge of the heated surface, and it grows in thickness with distance from the leading edge. The turbulent boundary layer is typically much thicker than the laminar boundary layer and is dominated by vortices and turbulent eddies. Free convection on the surface of a blunt body leads to the formation of a boundary layer that grows in thickness with distance from the surface leading edge and eventually leads to a rising plume. In external flow free convection, the processes at the surface that support natural convection do not influence the ambient conditions in any significant manner.
