Annu.Rev. Fluid Mech.1990.22:473-537 Copyright ©1990 by Annual Reviews Inc. All rights reserved LOCAL AND GLOBAL INSTABILITIES IN SPATIALLY DEVELOPING FLOWS Patrick Huerre 1 Department of Aerospace Engineering, University of Southern California, Los Angeles, California 90089-1191 Peter A. Monkewitz Department of Mechanical, Aerospace and Nuclear Engineering, University of California, Los Angeles, California 90024-1597 1. INTRODUCTION The goal of this survey is to review recent developments in the hydro- dynamic stability theory of spatially developing flows pertaining to absolute/convective and local/global instability concepts. We wish to dem- onstrate how these notions can be used effectively to obtain a qualitative and quantitative description of the spatio-temporal dynamicsof open shear flows, such as mixing layers, jets, wakes, boundary layers, plane Poiseuille flow, etc. In this review, weonly consider openflows where fluid particles do not remain within the physical domain of interest but are advected through downstreamflow boundaries. Thus, for the most part, flows in "boxes" (Rayleigh-B6nard convection in finite-size cells, Taylor-Couette flow between concentric rotating cylinders, etc.) are not discussed. Further- more, the implications of local/global and absolute/convective instability concepts for geophysical flows are only alluded to briefly. In many of the flows of interest here, the mean-velocity profile is non- ~Present address: D6partement de M6canique, Ecole Polytechnique, 91128 Palaiseau Cedex, France. 473 0066-4189/90/0115q3473 $02.00 www.annualreviews.org/aronline Annual Reviews Annu. Rev. Fluid. Mech. 1990.22:473-537. Downloaded from arjournals.annualreviews.org by University of California - San Diego on 04/27/06. For personal use only.