Recent Results in Laminar-Turbulent Transition

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 transitionalstructures 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