Inverse Solutions for Laminar Boundary-layer Flows with Separation and Reattachment

Inverse Solutions for Laminar Boundary-layer Flows with Separation and Reattachment
Author: James Edward Carter
Publisher:
Total Pages: 72
Release: 1975
Genre: Boundary layer
ISBN:

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Numerical solutions of the laminar, incompressible boundary-layer equations are presented for flows involving separation and reattachment. Regular solutions are obtained with an inverse approach in which either the displacement thickness or the skin friction is specified; the pressure is deduced from the solution. A vorticity--stream-function formulation of the boundary-layer equations is used to eliminate the unknown pressure. Solutions of the resulting finite-difference equations, in which the flow direction is taken into account, are obtained by several global iteration schemes which are stable and have unconditional diagonal dominance. Results are compared with Klineberg and Steger's separated boundary-layer calculations, and with Briley's solution of the Navier-Stokes equations for a separated region. In addition, an approximate technique is presented in which the streamwise convection of vorticity is set equal to zero in the reversed flow region; such a technique results in a quick forward-marching procedure for separated flows.

A Study of Non-Unique Solutions of the Two-Dimensional Boundary Layer Equations at Laminar Separation and Reattachment Points

A Study of Non-Unique Solutions of the Two-Dimensional Boundary Layer Equations at Laminar Separation and Reattachment Points
Author: M. Drela
Publisher:
Total Pages: 8
Release: 1981
Genre:
ISBN:

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The possibility of non-unique solutions to the laminar boundary equations in direct problem calculations has been identified for decelerating flow. For flows far from separation or reattachment one solution is physically reasonable and the others unrealistic. As a separation or reattachment point is approached, the multiple solutions approach each other and become identical. Understanding of this behavior allows direct problem calculations through separation, although such calculations are not practical. The computer code used to generate these results was developed to solve compressible, laminar or turbulent boundary layer and free wake problems in direct or inverse mode. The equation formulation uses a variable scaling based on the local displacement thickness rather than the more common Levy-Lees scaling or stream function form are possible.

Analytical Study of Subsonic Laminar Boundary Layer Separation and Reattachment Including Viscous-Inviscid Interaction

Analytical Study of Subsonic Laminar Boundary Layer Separation and Reattachment Including Viscous-Inviscid Interaction
Author: G. R. Inger
Publisher:
Total Pages: 53
Release: 1973
Genre:
ISBN:

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An approximate analytical theory is developed for predicting nonsimilar laminar boundary layer flows with separation, reversed flow and reattachment including subsonic viscous-inviscid interation, with application to a separation bubble problem. The analytical approach is based on a triple-deck flow model, the boundary layer being divided into two layers overlaid by a third region of interacting inviscid flow. It is shown that this model has a heretofore-unrecognized double-branched solution character that enables it to pass through separation and reattachment without signularities and provide a unified description over a wide range of both attached and reversed flow states. An iterative stream-wise pass method of calculation is devised which is free from the usual Crocco-Lees critical points occurring in interaction problems. Application to a specific example involving a linear adverse pressure gradient yields results in good agreement with an exact Navier-Stokes solution. (Author).

Separated Flow Studies

Separated Flow Studies
Author: Wilbur L. Hankey
Publisher:
Total Pages: 20
Release: 1975
Genre: Aerodynamics, Hypersonic
ISBN:

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This report reviews the progress over the last decade on separated flows conducted at these laboratories. Experimental investigations conducted in the hypersonic wind tunnels is discussed. Advancements are summarized in the theoretical area which cover the development of interacting boundary layers to the numerical computation of the complete Navier-Stokes equations.

Separated Flows

Separated Flows
Author: Jean J. Ginoux
Publisher:
Total Pages: 498
Release: 1966
Genre: Boundary layer
ISBN:

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