THE EFFECTS OF FREESTREAM PRESSURE-GRADIENT ON A CORNER BOUNDARY-LAYER

The incompressible boundary layer in the corner formed by two intersec ting perpendicular semi-infinite planes is investigated; the freestrea m flow, aligned with the corner, is of the form x(n), x* representing the streamwise distance from the leading edge. Similarity-type asympt otic solutions for large Reynolds numbers are derived and it, is found that solutions do not exist for all values of the parameter n, and th at for values of n where solutions do exist, non-uniqueness is a commo n feature; previous theoretical work has focused almost exclusively on the Blasius-type far field, corresponding to one of the n = 0 solutio ns. One corollary of the study is that in the case of a boundary-layer how over a hat plate with a distant bounding wall (or other crossflow irregularity) and zero streamwise pressure gradient, in addition to t he distant how taking the form of the Blasius similarity solution, a s econd similarity solution also exists, exhibiting a sizeable jet-like crossflow velocity component. The present work may help partly explain some of the difficulties reported in observing corner similarity-type flows experimentally. The question of asymmetrical solutions is also alluded to. A study is also made regarding the nature of the linear lo cal stability of the corner flow, and this indicates that the flow bec omes more stable with increasing positive values of n, and less stable with increasing negative values of n. Further, the critical Reynolds number for the local flow increases with increasing distance from the corner.