Drag Reduction on External Surfaces Induced by Wall Waves
Drag-reduction can be achieved by delaying of the onset of a turbulent flow as well as quenching turbulence itself. Due to the highly local nature of turbulent events and the rapid nature of breakdown a sensor-less (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 control strategies for boundary layer flows is limited and for bypass-transition none of the strategies has been successful. However, recent investigations indicate that sensorless (open-loop) control of transition to turbulence and drag reduction in turbulent flows is a feasible option.
KeywordsControl Region Drag Reduction Streamwise Velocity Boundary Layer Transition Streaky Structure
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