Time-dependent flows over textured or compliant surfaces: Turbulent drag reduction & compliant wall deformation

A significant part of the fuel used for transportation results from the drag in turbulent flows. Techniques for turbulent drag reduction yield associated reductions of the fuel consumption and greenhouse gas emissions, which is desirable from both economic and environmental perspectives (cf. chapter 1). This thesis investigates two passive techniques that could be exploited for the reduction of frictional drag in turbulent flows, namely textured and compliant surfaces. Correspondingly, the aim of the thesis is twofold, namely to explore the drag-reducing potential of riblet-textured surfaces, and to characterize the interaction between time-dependent (possibly turbulent) flows and a compliant wall. The work presented in this thesis was performed as part of the European project SEAFRONT, which aimed at the development of environmentally benign antifouling and dragreducing technologies for the maritime sector…