ABSTRACT
This chapter provides an introduction to convection by providing general equations of fluid mechanics and convection heat transfer. There are two categories of heat transfer involving fluids: forced convection and free or natural convection. In forced convection, the fluid flow is established by an external driving force provided by, say, a fan or pump. In natural convection, the fluid flow is caused by the buoyant effect resulting from heating or cooling the fluid. A fluid is a substance that deforms continuously under the action of an applied shear stress. Fluids at rest, or moving, experience some form of pressure variation, either with height or with horizontal distance. Surface tension is a measure of the energy required to reach below the surface of a liquid to bring molecules to the surface and form a new area. Streamlines are everywhere tangent to the velocity vector, and, for steady flow, a particle of fluid follows a path coincident with a streamline.
