1. Bursting and Structure of the Turbulence in an Internal Flow Manipulated by Riblets; S. Tardu, T.V. Truong, B. Tanguay. 2. On Near-Wall Turbulence-Generating Events in a Turbulent Boundary Layer on a Riblet Surface; Y.P. Tang, D.G. Clark. 3. Friction Velocity and Virtual Origin Estimates for Mean Velocity Profiles above Smooth and Triangular Riblet Surfaces; A.D. Schwarz-van Manen, A.F.M. van Geloven, J. Nieuwenhuizen, J.C. Stouthart, K.K. Prasad, F.T.M. Nieuwstadt. 4. Viscous Sublayers Analysis of Riblets and Wire Arrays; P. Luchini. 5. Riblet Flow Calculations with a Low Reynolds Number K - epsilon model; L. Djenidi, R.A. Antonia. 6. On the Prediction of Riblet Performance with Engineering Turbulence Models; B.E. Launder, S.P. Li. 7. Modelling the Time Dependent Flow over the Viscous Wall Region; S. Tullis, A. Pollard. 8. Possibility of Drag Reduction using d-Type Roughness; K.S. Choi, N. Fujisawa. 9. The Drag of Three-Dimensional Rectangualr Cavities; E. Savory, N. Toy, P.J. Disimile, R.G. DiMicco. 10. Turbulence Structure of Dilute Polymer and Surfactant Solutions in Artificially Roughened Pipes; H.-W. Bewersdorff, H. Thiel. 11. Effect of External Manipulators on the Heat Transfer on a Flat Plate Turbulent Boundary Layer; A. Hamdouni, J.P. Bonnet.

The thrust of modern research on turbulence in fluids is concerned with coherent structures and modelling. Riblets have been shown to reduce drag, and the papers presented in this volume tackle the main question of the mechanism responsible for this behaviour in turbulent flow. The contributions in this volume were presented at the Sixth Drag Reduction Meeting held at Eindhoven during November 1991. This volume will be a useful reference work for engineers, physicists and applied mathematicians interested in the topic of fluid turbulence.