Laminar Drag Reduction

The phenomenon of resistance to motion through a fluid is believed to be a function of fluid-wall interaction. This theory is based on the assumption that under certain conditions a real fluid does not usually slip on the wall in contact with it and displays laminar flow. This set of conditions is known as a ‘no slip boundary condition’. But if a fluid is passed alongside a wall, the drag reduction in the laminar flow region can be calculated. In Laminar Drag Reduction, the frictional drag of an internal or an external fluid flow along a certain kind of hydrophobic wall is investigated. An analytic approach towards the mechanism of drag reduction is employed using Navier-Stokes existence and smoothness equations. The experimental results presented in this book show that frictional drag of a fluid alongside this hydrophobic wall decreases in comparison with fluid flow along a conventional wall or surface. This form of laminar drag reduction represents a relatively new area of research, where the laminar flow can be controlled by microscopic surface modifications, allowing fluid flows to slip over a wall. Laminar Drag Reduction brings information about some interesting phenomena related to fluid slippage on a highly water-repellent surface. Readers, physics graduates and senior researchers alike, can benefit from the information presented in this book to tackle more challenging questions in fluid mechanics research.

------------------------------------------------------------ This volume contains the Proceedings of the CEAS/DragNet European Drag Reduction Conference held on 19-21 June 2000 in Potsdam, Germany. This conference, succeeding the European Fora on Laminar Flow Technology 1992 and 1996, was initiated by the European Drag Reduction Network (DragNet) and organised by DGLR under the auspice of CEAS. The conference addressed the recent advances in all areas of drag reduction research, development, validation and demonstration including laminar flow technology, adaptive wing concepts, turbulent and induced drag reduction, separation control and supersonic flow aspects. This volume which comprises more than 40 conference papers is of particular interest to engineers, scientists and students working in the aeronautics industry, research establishments or academia.

Maintenance of a laminar boundary layer by suction was suggested recently to decrease the friction drag of an immersed body, in particular an airfoil section [1]. The present treatise makes a theoretical contribution to this question in which, for several cases of suction and blowing, the stability of the laminar velocity profile is investigated. Estimates of the minimum suction quantities for maintaining the laminar boundary layer and estimates of drag reduction are thereby obtained.