Numerical Investigation of Classical and Bypass Transition in Streamwise Corner-flow

The laminar-turbulent transition of the flow in a zero-pressure-gradient streamwise corner is investigated by means of direct nu- merical simulation (DNS). Two basic scenarios are considered: transition caused by harmonic Tollmien-Schlichting type waves within the boundary-layer, and bypass transition triggered by homogeneous isotropic turbulence in the free-stream. In the first case, we further distinguish between waves that are symmetric, and waves that are anti-symmetric with respect to the corner bisector. It is found that turbulence originates from the corner in the classical boundary-layer transition scenario for both, symmetric and anti-symmetric perturbations. However, no such preference for the near-corner region is observed in bypass transition.