ABSTRACT
This chapter examines the flow in the boundary layer and its influence on the main flow and presents steady, two-dimensional flow of a constant-density fluid. It considers some of the features of boundary-layer flow are common to the velocity profiles that occur in fully developed flow through pipes. The chapter explains the increase of velocity with increasing distance from the solid surface that indicates shear stresses. With increasing distance from the solid surface the velocity approaches that of the main stream asymptotically, and there is no sharp dividing line between the boundary layer and the rest of the flow. The simplest boundary layer to study is that formed in the flow along one side of a thin, smooth, flat plate parallel to the direction of the oncoming fluid. Separation is caused by the reduction of velocity in the boundary layer, combined with a positive pressure gradient.
