On the breakdown of the wave packet trailing a turbulent spot in a laminar boundary layer

The evolution of two oblique wave packets trailing, a transitional spot in a laminar boundary layer was investigated in order to determine the extent of the interaction between the packets and the spot. The experimental investigation, carried out on two slightly different laminar boundary layers characterized by Falkner-Skan constants of β = 0 and β = 0.2, revealed that very small pressure gradients can have significant effects on the stability of the laminar boundary layer and the rate at which it is contaminated by a turbulent spot. Some simple, novel statistical procedures for treating the data were developed and were used to accentuate the understanding of the physical processes governing transition to turbulence.