The idea of organising a colloquium on turbulence emerged during the sabbatical leave of Prof. Arkady Tsinober in Zurich. New experimental observations and the insight gained through direct numerical simulations have been stimulating research in turbulence and are leading to the developments of new concepts. The organisers felt the necessity to bring together researchers who have contributed significantly to the advances in this field in a colloquium in which the current achievements and the future development in the theoretical, numerical and experimental approaches would be discussed. The main emphasis of the colloquium was put on discussions. These discussions led to an interesting and exciting exchange of ideas, but also involved its very laborious transcription onto paper. It was due to the personal efforts of Mrs. A. Vyskocil, Dr. N. Malik and Dr. X. Studerus that this work could be completed. The colloquium was held in the relaxed atmosphere of the Centro Stefano Franscini in Monte Verita near Ascona, a locality of exceptional natural beauty, which was put at our disposal by the Swiss Federal Institute of Technology. We would like to express our gratitude for this generous financial and logistic support, which contributed considerably to the success of the colloquium. Zurich, April 1993 Th. Dracos, A. Tsinober Participants Adrian, R. J. Kambe, T. Antonia, R. A. Kit,E. Aref, H. Landahl, M. T. Betchov, R. Lesieur, M. Bewersdorff, H. -W. Malik, N. Castaing, B. Moffatt, H. K. Chen, J. Moin,P. Dracos, T. Mullin, T. Frisch, U. Novikov, E. A.

Inhalt
Opening Address.- Session One..- Similarity Laws for Wall Turbulent Flows: Their Limitations and Generalizations.- A Prediction of the Multifractal Model: The Intermediate Dissipation Range.- A New View of Developed Turbulence.- Discussion.- Session Two..- On Vortices And Cascades in Turbulence.- A Dynamical Theory of Cascade in Turbulence and Non-Gaussian Statistics.- Small Scale Vortices in Turbulent Flows.- Discussion.- Session Three..- Spiral Structures in Turbulent Flow.- Solutions of Exact Kinetic Equations for Intermittent Turbulence.- How Important are Direct Interactions between Large and Small Scales in Turbulent Flows.- Discussion.- Session Four..- How Long is the Way from Chaos to Turbulence?.- Vortex Interactions as a Dynamical System.- Finite-dimensional Dynamics and Chaos in Fluid Flows.- Discussion.- Session Five..- The Origins of Turbulence.- Role of Algebraic Instability in Transition and Turbulence.- Active Control of Skin Friction and Separation in Certain Class of Wall-Bounded Flows.- Rapid Distortion Theory and the Structure of Turbulence.- Discussion.- Session Six..- A New Approach for Large Eddy Simulation of Turbulence and Scalar Transport.- On the Contribution of Multi-Point Experimental Techniques to the Study of Turbulence.- Direct Numerical Simulations and Hot Wire Experiments: A Possible Way Ahead?.- Small-Scale Structures in Turbulence: Their Implications for Turbulence Closures.- A Note on Local Isotropy in High-Reynolds-Number Turbulence.- Discussion.- Group Work.- Group I: Prospects of physical and numerical experiments for the fundamental understanding of turbulence.- Group II: Future implications of chaos theory, dynamical systems and prospects of low-dimensional descriptions of turbulent flows.- Group III: Reduction of non-linearityin turbulent flows further lines of research and their use in the development of the theory of turbulence.- Group IV: Prospects of statistical approaches to the turbulence problem how statistical methods, e.g. the theory of random fields, should be used in view of recent developments regarding the structure of turbulence, dynamical chaos, strange attractors, fractals.- Summary of the Symposium.- Discussion.