BOUNDARY-LAYER LINEAR-STABILITY USING A SYSTEM OF PARABOLIC EQUATIONS

The classical theory of laminar boundary layer linear stability assumes a quasi-parallel flow. This paper gives a first look at a new approach to this linear stability problem. Instead of solving an ordinary differential equation (the so-called ''Orr-Sommerfeld'' equation in the parallel theory), partial differential equations must be solved which are parabolic in the mean flow direction. Hence, from a global point of view, we have a problem of variation instead of an eigenvalue problem. The new approach is more flexible for an equivalent computing time. After describing the new approach, results obtained using it are compared with others from the classical theory, from direct numerical simulation, and from experiment.