ABSTRACT
A boundary layer is defined as the flow region next to a solid boundary where the flow field is affected by the presence of the boundary (Fig. 3.1). The concept was originally introduced by Ludwig Prandtl (1904). In the boundary layer, some momentum is gained by the flow region next to the boundary. Momentum is transferred from the main stream (or free stream) and contributes to the boundary layer growth. At the boundary itself, the velocity is zero. This is called the no-slip condition.
