The analogy of singularities in direct methods for calculating steady three dimensional and unsteady two dimensional boundary layers: Analysis of reversed modes
Abstract
The problem of occurrence of singularities in boundary layer equations, both in the unsteady twodimensional and steady threedimensional cases, is analytically studied by means of the global equations of momentum and entrainment. In the direct mode the velocity is given. It is shown that in opposition to the steady twodimensional case, the occurrence of reversed flows does not generally create singularities, but indicates a downstream influence. In both cases, the analytical and numerical study shows that discontinuity lines can exist, corresponding to weak solutions of the equations, but these lines have no physical meaning. Particularly in the threedimensional case they must not be confused with separation lines. The calculations in the inverse mode avoid any singularity. The velocity is then an unknown of the boundary layer problem. Such methods are useful to solve the coupling problem between viscidinviscid flow and are also interesting to verify closure relations of calculation models in separated regions.
 Publication:

In AGARD Computation of ViscousInviscid Interactions 14 p (SEE N8126037 1701
 Pub Date:
 February 1981
 Bibcode:
 1981cvii.agar.....C
 Keywords:

 Boundary Layer Equations;
 Reversed Flow;
 Singularity (Mathematics);
 Three Dimensional Boundary Layer;
 Two Dimensional Boundary Layer;
 Boundary Layer Stability;
 Inversions;
 Numerical Analysis;
 Steady Flow;
 Unsteady Flow;
 Fluid Mechanics and Heat Transfer