Global instability methods are becoming an increasing useful tool in investigations of  the stability of highly non-parallel flows.

In this approach eigenfunctions are sought proportional to exp( Lambda . t) and this leads to a partial differential eigenvalue problem in the spatial variables to be solved. We will discuss our recent work on applying these ideas to study a variety of quite different flow problems

including the  stability of lid-driven cavity flows as well as the stability of subsonic and supersonic laminar separated flows past concave/convex corners.