The Seventh Symposium was held on the campus of Stanford University with*a combination offacilities and weather which made it possible to add open-air poster sessions and coffee breaks to the programme. This was particularly convenient as the call for papers attracted close to three hundred abstracts and a total number of participants well in excess of this number. Some one hundred and thirty papers were presented in carefully phased parallel sessions and thirty six further contributions were made available in the form of posters. In addition, a lively open-forum session allowed additional speakers to make brief presentations. The staff of the Thermo-Sciences Division of the Department of Mechanical Engineering at Stanford undertook the local arrangements with evident success and their extensive record of contributions to Turbulent Shear Flows made the venue particularly appropriate. Also, the Centre for Turbulence Studies, based on the faculty of the University and the NASA Ames Research Center, provided a considerable body of expertise with emphasis on direct numerical stimulation.

Since the inaugural symposium at the Pennsylvania State University in 1977, the venues for the series of biennial symposia on turbulent shear flows have alternated between the USA and Europe. For the Sixth Symposium, the first to be held in France, the city of Toulouse proved a natura] choice, being a centre for the aerospace industry, meteorological research and higher education. The meeting was hosted by the Paul Sabatier University on the southern perimeter of the city, and there nearly 300 workers in the field of turbulence converged to pronounce upon, debate and absorb the current issues in turbulent shear flows and to enjoy the unfailing September sunshine. The meeting had attracted more than 200 offers of papers from which just over 100 full papers and about 20 shorter communications in open forums could be accommodated. The present volume contains 28 of the original symposium presentations selected by the editors. Each contribution has been revised by its authors - sometimes quite extensively -in the light of the oral presentation. It is our hope that the selection provides a substantial statement of permanent interest on current research in the five areas covered by this book, i.e. fundamentals and closures, scalar transport and geophysical flows, aerodynamic flows, complex flows, and numerical simulations.

The inaugural Symposium on Turbulent Shear Flows was held at The Pennsylvania State University in 1977. Thereafter the locations for the biennial symposium have alternated between the USA and Europe. However, the ninth Symposium on Turbu lent Shear Flows was awarded to Japan in recognition of the strong support researchers of the Pacific Rim countries have given previous symposia. The University of Kyoto was the host institution and the meeting was held in the Inter national Conference Hall. The Local Arrangements Committee did a superb job scheduling traditional Japanese dinners and arranging visits to the many cultural treasures in the Kyoto region. The meeting attracted more than 260 offers of papers. Thirty-three sessions were scheduled to accommodate the 138 papers accepted for oral presentation. In addition a poster session was scheduled on each of the three days to accommodate a total of 42 poster presentations. From the presentations at the symposium 24 have been selected for inclusion in this volume. The authors of these papers have revised them taking into consideration comments made during their oral presentation and recommendations made by the Editors. Four subject areas are identified, namely closures and fundamentals, free flows, wall flows, and combustion and recirculating flows. Eminent authorities have prepared introductory articles fot each topic to put the individual contributions in context with each other and with related research.

The first four symposia in the series on turbulent shear flows have been held alternately in the United States and Europe with the first and third being held at universities in eastern and western States, respectively. Continuing this pattern, the Fifth Symposium on Turbulent Shear Flows was held at Cornell University, Ithaca, New York, in August 1985. The meeting brought together more than 250 participants from around the world to present the results of new research on turbulent shear flows. It also provided a forum for lively discussions on the implications (practical or academic) of some of the papers. Nearly 100 formal papers and about 20 shorter communications in open forums were presented. In all the areas covered, the meeting helped to underline the vitality of current research into turbulent shear flows whether in experimental, theoretical or numerical studies. The present volume contains 25 of the original symposium presentations. All have been further reviewed and edited and several have been considerably extended since their first presentation. The editors believe that the selection provides papers of archival value that, at the same time, give a representative statement of current research in the four areas covered by this book: - Homogeneous and Simple Flows - Free Flows - Wall Flows - Reacting Flows Each of these sections begins with an introductory article by a distinguished worker in the field.

This volume contains a selection of the papers presented at the Eighth Symposium on Turbulent Shear Flows held at the Technical University of Munich, 9-11 September 1991. The first of these biennial international symposia was held at the Pennsylvania State Uni versity, USA, in 1977; subsequent symposia have been held at Imperial College, London, England; the University of California, Davis, USA; the University of Karlsruhe, Ger many; Cornell University, Ithaca, USA; the Paul Sabatier University, Toulouse, France; and Stanford University, California, USA. The purpose of this series of symposia is to provide a forum for the presentation and discussion of new developments in the field of turbulence, especially as related to shear flows of importance in engineering and geo physics. From the 330 extended abstracts submitted for this symposium, 145 papers were presented orally and 60 as posters. Out of these, we have selected twenty-four papers for inclusion in this volume, each of which has been revised and extended in accordance with the editors' recommendations. The following four theme areas were selected after consideration of the quality of the contributions, the importance of the area, and the selection made in earlier volumes: - wall flows, - separated flows, - compressibility effects, - buoyancy, rotation, and curvature effects. As in the past, each section corresponding to the above areas begins with an introduction by an authority in the field that places the individual contributions in context with one another and with related research.