Unsteady Separation Phenomena in a Two-Dimensional Cavity

Introduction I is generally recognized that the problem of separation is very important in practical aerodynamics and in many other fluid flowfields. Although a great deal of theoretical work has been done on steady separation, mostly through the use of the boundary-layer equations, the unsteady situation has received little attention in spite of its significance. Because the boundarylayer approximation is incomplete, recourse has been made to the full momentum equation. A two-dimensional oscillatory cavity flow presents a tractable model for approximate finite-difference solution of the equation to study the unsteady separation process. Although other workers have used steady cavity flow models, this is the first time an oscillatory cavity.flow solution has been published. The results are first compared to the steady case where there is only one fixed separation streamline along the line of symmetry. Then a dynamic pattern of separation and reattachment is illustrated.