Structure of Turbulence and Drag Reduction: IUTAM Symposium Zurich, Switzerland July 25–28, 1989 (IUTAM Symposia)

In 1976 a similar titled IUTAM Symposium (Structure of Turbulence and Drag Reduction) was held in Washington . However, the progress made during the last thirteen years as weil as the much promising current research desired a second one this year. In Washington drag reduction by additives and by direct manipulation of the walls (compliant walls and heated surfaces) were discussed. In the meantime it became evident that drag reduction also occurs when turbulence is influenced by geometrical means, e.g. by influencing the pressure distribution by the shape of the body (airfoils) or by the introduction of streamwise perturbances on a body (riblets). In the recent years turbulence research has seen increasing attention being focused on the investigation of coherent structures, mainly in Newtonian fluids. We all know that these structures are a significant feature of turbulent flows, playing an important role in the energy balance in such flows. However their place in turbulence theories as weil as the factors influencing their development are still poorly understood. Consequently, the investigation of phenomena in which the properties of coherent structures are alte red provides a promising means of improving our understanding of turbulent flows in general. Front Matter....Pages I-XXVI Front Matter....Pages 1-1 Turbulent Boundary Layer Structure: Progress, Status, and Challenges....Pages 3-22 A Review of Vortex Structures and Associated Coherent Motions in Turbulent Boundary Layers....Pages 23-50 Hairpin Vortices in Turbulent Boundary Layers: The Implications for Reducing Surface Drag....Pages 51-58 Production of Turbulence in Boundary Layers and Potential for Modification of the near Wall Region....Pages 59-68 Visualisation of the Organized Motion in a Turbulent Boundary Layer....Pages 69-75 Analysis of Experimental Data on Boundary Layer Pressure Fluctuations in Turbulent Pipe Flow....Pages 77-84 Behaviour of Separation Bubble with Different Roughness Elements at the Leading Edge of a Flat Plate....Pages 85-92 Organized Structures and Transition in the Near Field of a Plane Jet....Pages 93-100 Determination of Regular Structures in Turbulent Mixing Processes by Raman Scattering....Pages 101-108 Wall Layer Eruptions in Turbulent Flows....Pages 109-118 Non-Linear Coherent Mode Interactions and the Control of Shear Layers....Pages 119-127 Wavenumber-Frequency Spectral Densities of Turbulent Wall Pressure and Wall Shear Fluctuations....Pages 129-136 Quadrant Analysis and Instantaneous Momentum Transport—a Critical Review....Pages 137-144 Artificial Control of Turbulent Mixing Layers....Pages 145-152 Front Matter....Pages 153-153 Dynamics of Dilute Polymer Solutions....Pages 155-185 The Effect of Dilute Polymer Solutions on Viscous Drag and Turbulence Structure....Pages 187-200 Aspects of Mechanisms in Type B Drag Reduction....Pages 201-213 Change of Structures Close to the Wall of a Turbulent Flow in Drag Reducing Fluids....Pages 215-222 The Influence of Polymer Additives on the Coherent Structure of Turbulent Channel Flow....Pages 223-232 Interaction of Molecules and Turbulent Flow in Dilute Polystyrene Solutions....Pages 233-240 Front Matter....Pages 153-153 Λ-Shaped Vortices in Dilute Polymer Solutions....Pages 241-248 Wake Flows in Dilute Polymer Solutions....Pages 249-255 Drag Reduction Caused by the Injection of a Polymer Solution into a Pipe Flow....Pages 257-274 Large Eddies and Polymer Strings....Pages 275-281 Friction Drag Reduction by Injection of Polyethyleneoxide Solution in a Turbulent Boundary Layer Through Slot and Perforated Section....Pages 283-290 Front Matter....Pages 291-291 Drag Reduction in Surfactant Solutions....Pages 293-312 Turbulent Drag Reduction Versus Structure of Turbulence....Pages 313-340 Drag Reduction by Sand Grain Roughness....Pages 341-348 Effect of Wall Suction on the Transport of a Scalar by Coherent Structures in a Turbulent Boundary Layer....Pages 349-356 Flow Control by Suction....Pages 357-360 Inertial Interaction of Spherical and Fibre-like Solid Particles with Turbulent Flowing Liquids....Pages 361-368 Front Matter....Pages 369-369 Hydrodynamic Instability and Coherent Structures in Turbulence....Pages 371-397 Effect of Three-dimensional Surface Elements on Boundary Layer Flow....Pages 399-406 Interpretation of Polymer Drag Reduction in Terms of Turbulence Producing Eddies Close to the Wall....Pages 407-415 Active Turbulence Control in Wallbounded Flow Using Direct Numerical Simulations....Pages 417-425 Front Matter....Pages 427-427 Drag Reduction by Passive Devices—a Review of some Recent Developments....Pages 429-465 Relation Between Outer Structures and Wall-layer Events in Boundary Layers with and without Manipulation....Pages 467-474 Boundary Layer Manipulators at High Reynolds Numbers....Pages 475-482 Large-scale Turbulence Structures in a Manipulated Channel Flow....Pages 483-493 Analysis of the Wake of an Outer Layer Manipulator....Pages 495-502 Front Matter....Pages 427-427 Panel Discussions....Pages 585-610 Influence of an Acoustic Field on the Flow Structure Behind a LEBU in a Turbulent Boundary Layer....Pages 503-506 Analysis of the Structure of a Turbulent Boundary Layer, with and without a LEBU Using Light Sheet Smoke Visualizations and Hot Wire Measurements....Pages 507-515 The Effects of Longitudinal Roughness Elements and Local Suction upon the Turbulent Boundary Layer....Pages 517-524 Turbulent Drag Reduction by Nonplanar Surfaces — A Survey on the Research at TU/DLR Berlin....Pages 525-543 Drag Reduction in Pipes Lined with Riblets....Pages 545-551 Drag Reduction Mechanisms and Near-wall Turbulence Structure with Riblets....Pages 553-560 The Bursting Process over Drag Reducing Grooved Surfaces....Pages 561-568 Riblets in Internal Flows with Adverse Pressure Gradients....Pages 569-576 Experimental Investigation of Turbulent Boundary Layers Manipulated with Internal Devices: Riblets....Pages 577-584