Numerical simulation of transition in three dimensional boundary layers

Linear and nonlinear stages of laminar/turbulent transition in a three dimensional boundary layer, initiated by cross flow instability, are investigated using stability theory and numerical simulation of the incompressible Navier-Stokes equations. The conditions in the calculations are matched to those of a transition experiment for a swept, flat plate. Falkner-Skan-Cooke similarity profiles are used to describe the basic parallel flow. A quasi two dimensional treatment of the problem produces a nonlinear saturation of the stationary cross flow vortices. The nonlinear interaction between the stationary vortices and traveling waves is investigated in more detail. The development of the mean flow, fluctuations and instantaneous flow parameters is documented. The development of the flow depends strongly upon the initial perturbations that are chosen. In general, good agreement is observed between comparable stages of simulation and experiment. The nonlinear interactions produce a marked distortion of the streamwise and crossflow profiles and an increase in mean wall shear stress.