Flow Separation.

The calculation of laminar separation has always represented one of the most relevant problems of boundary layer theory, even within the classical Prandtls assumption of vanishing transverse pressure gradients. However, the validity of this assumption is in question not only in certain problems of supersonic separation where the classical theory cannot provide an answer, but also in the simplest incompressible problems. Recent theories attempting to calculate separation after relaxing Prandtls assumption are reveiwed in this paper. Purely numerical results based on the finite difference solution of the complete Navier-Stokes equations were considered to be beyond the scope of this review and are just briefly mentioned. An analytical procedure based on multiple layer treatment is discussed. A third procedure of interest is the generalization of von Karman momentum integral procedure taking into account the existence of transverse pressure gradients.