Some thoughts on boundary layer transition

The subject of boundary-layer transition is a vast and long-pending one, but in the present paper it is intended to discuss only a limited number of phenomena, especially those which are not only essential for affording a correct understanding of the basic feature of transition, but also adequate for systematizing the writer's own thoughts on the problem of transition. The phenomena selected are the instability for finite disturbances, the three-dimensional feature of instability, the breakdown of wave motion, and the transition induced by roughness element. Consideration is restricted to the two-dimensional basic flow of an incompressible fluid over a flat plate with zero pressure gradient (Blasius flow), or between two parallel plates with falling pressure gradient (plane Poiseuille flow). (orig.)