Question

Is tollmien-schlichting wave necessary for transition of zero pressure gradient boundary layer ow?

Answer 1

Answer:

Comprehensive understanding of the routes of instability and transition for many flows is not complete yet. For a zero pressure gradient (ZPG) boundary layer, linear spatial theory predicted Tollmien-Schlichting (TS) waves, which have been experimentally verified by vortically exciting the flow by a monochromatic source.

Explanation:

Answer 2

We have now grown to the idea of any discussion on instability and transition for external flow, starting with the existence and necessary condition of creating Tollmien-Schlichting wave for zero pressure gradient boundary layer, for infinitesimally small disturbances.