
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 twodimensional steadystate case, Prandtl's criterion (vanishing of skin friction) appears to be successful in predicting separation. Numerical integrations have indicated that the boundarylayer 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 'boundarylayer 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 threedimensional 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