Threedimensional stability of growing boundary layers
Abstract
A theory is developed for the linear stability of threedimensional growing boundary layers. The method of multiple scales is used to derive partialdifferential equations describing the temporal and spatial evolution of the complex amplitudes and wavenumbers of the disturbances. In general, these equations are elliptic unless certain conditions are satisfied. For a monochromatic disturbance, these conditions demand that the ratio of the components of the complex group velocity be real and thereby relate the direction of growth of the disturbance to the disturbance wave angle. For a nongrowing boundary layer, this condition reduces to dalpha/dbeta being real, in agreement with the result obtained by using the saddlepoint method. For a wavepacket, these conditions demand that the components of the group velocity be real.
 Publication:

LaminarTurbulent Transition
 Pub Date:
 1980
 Bibcode:
 1980ltt..proc..201N
 Keywords:

 Boundary Layer Flow;
 Boundary Layer Stability;
 Perturbation Theory;
 Three Dimensional Boundary Layer;
 Wave Propagation;
 Elliptic Differential Equations;
 Laminar Flow;
 Monochromatic Radiation;
 Parallel Flow;
 Partial Differential Equations;
 Saddle Points;
 Wave Packets;
 Fluid Mechanics and Heat Transfer