Spanwise-Periodic Three Dimensional Disturbances in Nominally 2-D Separating Laminar Boundary Layer Flows. Part One. Theoretical Formulation.

摘要

The results of a preliminary investigation on the stability of a nominally-two-dimensional laminar boundary layer flow approaching the separation point with respect to 3-D periodic spanwise disturbances, under the hypothesis that a steady state is reached, are presented. The basic equations of the disturbances are examined with an assumed form of the 3-D perturbations, resulting in a system of ordinary differential equations. Together with the boundary conditions requiring the disturbances to be zero at the wall and to vanish asymptotically at infinity, a two-point eigenvalue problem was formulated. Meksyn's method was adapted for the calculation of the basic two-dimensional flow parameters entering the equations in the region near the separation point. This method requires that the experimentally determined streamwise variation of the pressure at the edge of the boundary layer be known a priori. (Author)