A predicable condition for boundary layer separation of 2-D   incompressible fluid flows
  In this paper, the solutions of Navier-Stokes equations with Dirichlet boundary conditions governing 2-D incompressible fluid flows are considered. A condition for boundary layer separation, which is determined by initial values and external forces, is obtained. More importantly, the condition can predict directly when and where boundary layer separation will occur. The main technical tool is geometric theory of incompressible flows developed by T. Ma and S.Wang. 
Hong Luo, Quan Wang, Tian Ma
physics.flu-dyn