ABSTRACT
This chapter provides the basic concept of boundary-layer flow and heat transfer. It focuses on how to derive two-dimensional boundary-layer conservations for mass, momentum, and energy; boundary-layer approximations; non-dimensional analysis; and Reynolds analogy. For flow moving over a solid body, a hydrodynamic (or velocity) boundary layer is formed near the solid surface. In general, hydrodynamic boundary-layer thickness grows with the square root of distance from the leading edge of the flat plate. Since velocity gradient decreases (because boundary-layer thickness grows) with increasing distance due to viscosity, shear stress (related to pressure loss) and friction factor decrease with increasing distance from the leading edge of the flat plate. For hot flow moving over a cold solid body, a thermal (temperature) boundary layer is formed around the solid surface. Many real-life applications for flow moving over a solid body can be modeled as a two-dimensional boundary-layer flow and heat transfer problems.
