The final approach to steady, viscous flow near a stagnation point following a change in free stream velocity

Abstract

The flow field near a stagnation point in two-dimensional, incompressible, viscous flow is considered to change with time in such a way that the inviscid flow is steady after some given finite instant of time. The final approach to steady flow throughout the field is shown to be characterized by exponential decay with time of perturbations from the steady velocity field. The characteristic factors in the exponents arise from the solution of an eigenvalue problem in ordinary linear differential equations.Similar behaviour exists for the axially symmetric case. A comparable analysis furnishes, however, a meaningless result in the case of a two-dimensional, semiinfinite flat plate which is moving in its own plane, normal to its leading edge.