The evolution of a localized disturbance in a laminar boundary layer
Abstract
NavierStokes calculations simulate the evolution of a localized disturbance in a flat plate boundary layer. It is found that, in accordance with previous results, the evolving disturbance consists of two parts: an advective portion which reflects the structure of the initial disturbance and which travels at approximately the local mean velocity, and a dispersive wave portion which grows or decays according to TollmienSchlichting instability theory. The advective portion grows much more rapidly than the wave portion and gives rise to two distinct nonlinear effects. The first is the appearance of a lowspeed streak, bounded in the vertical and spanwise directions by intense shear layers. The second nonlinear effect is the onset of a secondary instability on the vertical shear layer giving rise to oscillations in the vertical and spanwise components of velocity.
 Publication:

LaminarTurbulent Transition
 Pub Date:
 1990
 Bibcode:
 1990ltt..proc..189B
 Keywords:

 Boundary Layer Stability;
 Flat Plates;
 Laminar Boundary Layer;
 NavierStokes Equation;
 TollmienSchlichting Waves;
 Laminar Flow;
 Power Spectra;
 Shear Layers;
 Fluid Mechanics and Heat Transfer