EVOLUTION OF DISTURBANCES IN STAGNATION-POINT FLOW

The evolution of three-dimensional disturbances in an incompressible t hree-dimensional stagnation-point flow in an inviscid fluid is investi gated. Since it is not possible to apply classical normal-mode analysi s to the disturbance equations for the fully three-dimensional stagnat ion-point flow to obtain solutions, an initial-value problem is solved instead. The evolution of the disturbances provides the necessary inf ormation to determine stability and indeed the complete transient as w ell. It is found that when considering the disturbance energy, the pla nar stagnation-point flow, which is independent of one of the transver se coordinates, represents a neutrally stable flow whereas the fully t hree-dimensional flow is either stable or unstable, depending on wheth er the flow is away from or towards the stagnation point in the transv erse direction that is neglected in the planar stagnation point.