Calculation of unsteady turbulent boundary layers in direct or inverse mode, including reverse flows: Analysis of singularities
Abstract
The nature of the system of the unsteady turbulent boundary layer equations is investigated through the global equations of continuity, momentum and entrainment, either in the direct mode, or in the inverse mode. In the direct mode, with a prescribed pressure, it is shown that, unlike the steady case and a few particular flows excepted, the occurrence of reversed flow does not generate a singularity, but acutally involves the existence of an upstream influence. In the case of an inverse mode, the problem is closed with a prescribed evolution, either for a characteristic quantity of the boundary layer (for example the displacement thickness), or for a parameter which should be deduced from a coupling with the inviscid flow. It is shown that an inverse unsteady integral method of practical interest can be defined for configurations including reverse flow, and that a numerical integration marching from upstream to downstream is then still possible.
 Publication:

In its La Rech. Aerospatiale
 Pub Date:
 1980
 Bibcode:
 1980ReAeB........3C
 Keywords:

 Reversed Flow;
 Singularity (Mathematics);
 Turbulent Boundary Layer;
 Unsteady Flow;
 Boundary Layer Separation;
 Inviscid Flow;
 Numerical Integration;
 Fluid Mechanics and Heat Transfer