External Manipulators (LEBUs) -- Balance of turbulent kinetic energy downstream a single flat, plate manipulator : comparisons between detailed experiments and modelling. -- Manipulation and modelling of turbulent pipe flow : some parametric studies of single and tandem ring devices. -- Large eddy simulation of manipulated boundary layer and channel flows. -- The importance of LEBU device shape for turbulent drag reduction. -- Internal Manipulators (Riblets) -- Boundary layer flow visualisation patterns on a riblet surface. -- Simultaneous flow visualisation and LDA studies over longitudinal micro-grooved surfaces. -- Effects of longitudinal pressure gradients on turbulent drag reduction with riblets. -- Synthesis of experimental riblet studies in transonic conditions. -- Effect of riblets on either fully developed boundary layers or internal flows in laminar regime. -- Internal and External Manipulators -- Turbulent boundary layer over a ribleted surface with tandem manipulators using surface drag balances. -- List of referees.