Accession Number : AD0717772

Title :   Boundary Layer Separation.

Descriptive Note : Doctoral thesis,

Corporate Author : CORNELL UNIV ITHACA N Y GRADUATE SCHOOL OF AEROSPACE ENGINEERING

Personal Author(s) : Telionis,Demetrios Pyrros

Report Date : SEP 1970

Pagination or Media Count : 147

Abstract : The phenomenon of separation is one of the most critical features of the flow of viscous fluids about rigid bodies. In the two-dimensional steady-state case, Prandtl's criterion (vanishing of skin friction) appears to be successful in predicting separation. Numerical integrations have indicated that the boundary-layer equations behave singularly at separation, and Goldstein has suggested analytical formulas describing this situation. Prandtl's criterion fails to predict meaningful separation for unsteady problems and this seems to have been mostly unnoticed. A general and formal definition of 'boundary-layer separation' is given, based on the concept of Goldstein's singularity. It is demonstrated how from this definition one can deduce meaningful criteria for the unsteady problem as well as other complicated cases, such as three-dimensional or compressible separation flow. A simple formula is suggested for the component of the velocity in the direction parallel to the wall; and it is demonstrated that this is in agreement with Goldstein's results for small distance from separation along the wall. A differential equation is derived from the momentum equation which contains the velocity profile at separation. A few applications are included, demonstrating solutions of this equation, which, in the unsteady case, contains the velocity of the phenomenon of separation too.

Descriptors :   (*FLOW SEPARATION, THEORY), (*BOUNDARY LAYER, SEPARATION), EQUATIONS OF MOTION, MATHEMATICAL PREDICTION, DIFFERENTIAL EQUATIONS, APPROXIMATION(MATHEMATICS), STAGNATION POINT, VELOCITY, WALLS, MOMENTUM, THESES

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE