Finite Disturbance Effect on the Stability of a Laminar Incompressible Wake Behind a Flat Plate

An integral method is used to investigate the interaction between the stability of a single frequency finite amplitude disturbance with the non-parallel mean flow in a laminar, incompressible wake behind a flat plate. The mean flow is assumed to be characterized by a few shape parameters. The integrals involving the fluctuating components are determined as functions of those shape parameters by solving the inviscid Rayleigh equation of the linear stability theory using the local mean flow. The variations of the amplitude of the fluctuation and the mean flow in the streamwise direction are then determined from solving the set of ordinary differential equations. The effect of coupling between the mean flow and the fluctuation was found to be very important. The calculations show good agreement with the experimental data of Sato and Kuriki.