This special issue is intended to provide a snapshot of current research in the área of "Global Flow Instability and Control". The original papers, and to a certain extent the topic itself, are intimately linked with the series of symposia by the same ñame that were held in Crete, Greece, between 2001 and 2009. As members of the organizing committees of the Crete symposia, we invited all past participants to contribute, and all papers were reviewed following the strict standards of the journal. This preface gives a brief historical account of events that have shaped ideas in the fleld over the past decade, followed by a synopsis of the papers published herein.
Keyword Global flow instability and control
The Crete meetingsIn July 1998, Peter Duck and Anatoly Ruban organized the EUROMECH 384 CoUoquium on "Steady and Unsteady SeparatedFlows" in Manchester, with Sir James Lighthill as the keynote speaker. The proceedings of this colloquium were published as a Research Frontiers issue, volume 358, of the Philosophical Transactions of the Royal Society London journal. The preface of that issue contains the colourful hand-written transparencies of Sir James, which were bound to be the last scientiflc document written by this towering fluid mechanics figure. A summary versión of another set of hand-written colourful drawings, corresponding to the hour-long presentation of Uwe Dallmann on flow topology [6], was included as the last chapter of the three-part paper by Theofilis, Hein and Dallmann [39] and provided a qualitative description of the first quantitative discovery, via a partial-differential-equation (PDE)-based eigenvalue problem (EVP) solution, of what is now commonly called global mode of a laminar separation bubble. One of the highlights in the prematurely ended scientiflc career of Uwe Dallmann was the enthusiastic appreciation of his flow topology work by Sir James, which is only natural, given that the first appearance of the association between flow separation and flow topology was the work of Lighthill himself in the classic textbook of Rosenhead [19].