Gortler vortices in boundary layers with streamwise pressure gradient: Linear theory

Linear theory is used to analyze the stability of two-dimensional boundary layer flows to stationary Gortler vortices. The basic flow profiles in the boundary layer are described by the Falkner-Skan similarity solutions. We approach the problem both with local linear theory (with the streamwise position held fixed) and with a streamwise marching technique (to represent the evolution of the inlet disturbance). Comparisons of solutions obtained by the two methods are presented: The results are consistent in showing that adverse pressure gradients are destabilizing, as in the case of Tollmien-Schlichting waves. This is at odds with recent findings by Otto and Denier and underscores the sensitivity of the results to initial conditions. (C) 1996 American Institute of Physics.