Some Characteristics of Unsteady Two- and Three-Dimensional Reversed Boundary-Layer Flows

The purpose of this investigation is to study some of the characteristics of unsteady two- and three-dimensional boundary-layer flows with flow reversal. The primary focus of the study will be the time development of the flow-reversal region due to adverse pressure gradients, and differences between two- and three-dimensional flows. Some other features which have been investigated are the following: (a) determination of the existence of steady solutions with flow reversal; (b) development of a generalized coordinate transformation to remove singularities due to leading edges and impulsive starting; and (c) development of a numerical method for integrating the two-and three-dimensional equations in flow-reversed regions. Since these topics cover a very large range of material, the three-dimensional investigations have been limited to flows along a line of symmetry where the influence of three-dimensionality is felt through the cross-flow derivative. However, the addition of cross flow does exert a very substantial influence on the structure of the boundary layer, as will be seen in this paper.