Drag Reduction on External Surfaces Induced by Waves
|Research Area||DNS of the effect of travelling waves to infer reduced drag|
|Principal Investigator(s)||Dr. H.C. de Lange|
The reduction of the viscous drag force exerted on bodies (e.g. wings, cars, etc) moving in a fluid is of great technical interest (for example for drag reduction of airplanes). One of the mayor keys to drag-reduction is the delay of breakdown to and decay of turbulence in the boundary layer. Due to the highly local nature of turbulence and the rapid nature of breakdown a sensorless (open-loop) strategy is highly preferable, since it prevents the necessity of large numbers of fast sensor/actuator combinations. Thus far, the success of the delay/decay techniques on boundary layer flows with noise is limited and for bypass-transition none of the strategies has been successful. In this project a detailed numerical study of the mechanisms to reduce the drag in a boundary layer will be performed on three modal-based options: Upstream traveling waves (UPTW), Spanwise traveling waves (SPTW) and Control by streaks (CBS). The DNS (Direct Numerical Simulation) results will be used to open the opportunity to optimize the drag reduction, i.e. to 'continuously' vary the input wave-properties or streak-configuration.