Recent Results in Laminar-Turbulent Transition

This volume contains 24 papers presented at the international concluding colloquium of the German priority programme (DFG-Verbundschwerpunktprogramm) "Transition", held in April 2002 in Stuttgart. The unique and successful programme ran six years starting April 1996, and was sponsored mainly by the Deutsche Forschungsgemeinschaft, DFG, but also by the Deutsches Zentrum für Luft-und Raumfahrt, DLR, the Physikalisch-Technische Bundesanstalt Braunschweig, PTB, and Airbus Deutschland. The papers summarise the results of the programme and cover transition mechanisms, transition prediction, transition control, natural transition and measurement techniques, transition - turbulence - separation, and visualisation issues. Three invited papers are devoted to mechanisms of turbulence production, to a general framework of stability, receptivity and control, and a forcing model for receptivity analysis. Almost every transition topic arising in subsonic and transonic flow is covered.

Contenu

Invited Lectures.- On a universal mechanism of turbulence production in wall shear flows.- A general framework for stability, receptivity and optimal control.- The equivalent forcing model for receptivity analysis with application to the construction of a high-performance skin perforation pattern for LFC.- 1 Transition Mechanisms.- DNS investigations on the laminar breakdown in a three-dimensional boundary-layer flow.- Absolute/convective instability investigation of primary and secondary crossflow vortices.- Direct numerical simulation of the development of asymmetric perturbations at very late stages of the transition process.- Systematic investigations of 3D acoustic receptivity with respect to steady and unsteady disturbances. Experiment and DNS.- Three-dimensional steady disturbance modes in the Blasius boundary layer - a DNS study.- 2 Transition Prediction.- Industrial view on transition prediction.- Nonlinear nonlocal transition analysis - code development and results -.- Direct numerical simulation of instabilities in the compressible swept Hiemenz flow.- A combined numerical and experimental investigation of transition in a laminar separation bubble.- 3 Transition Control.- Generation and control of oblique Tollmien-Schlichting waves in a Blasius boundary layer.- DNS study of discrete suction in a 3-D boundary layer.- Active control of boundary-layer instabilities on an unswept wing.- Numerical investigations of active control of boundary-layer instabilities.- On the potential and the limitations of boundary-layer stabilization via active wave cancellation.- 4 Natural Transition and Measurement Techniques.- High resolution boundary layer profile sensors.- Propagation of Tollmien-Schlichting waves in a wing boundary layer.- Investigation of transitional structures in artificially excited boundary layer flows by means of stereo and multi-plane PIV.- Experimental investigations of natural and controlled transition on a laminar flow airfoil.- A hot-film measuring system for free flight conditions.- 5 Transition-Turbulence-Separation.- Comparison of two large-eddy simulations for a stalled airfoil flow using different finite-volume formulations.- Vernetzte Projektgruppen.- Visualization of unsteady flow structures in a high-performance computing environment.- Index of authors.