Some similarity in the breakdown process of the primary instability between 2-D and 3-D boundary layers

Through investigation in 3-D boundary-layers around rotating bodies and curved walls, some similarity in the breakdown process of the primary instability with that of 2-D boundary-layer was observed. The behaviour of the shedding eddies (secondary disturbance) which appear at the final stage of the primary instabilities (centrifugal and crossflow vortices, etc.) are remarkably similar to the breakdown process of the Tollmien-Schlichting wave except that the beginning of so called 'new instability' is not so dramatic as 2-D case which accompanies the 'spikes'.