Attenuation of Vortex Shedding by Model-Based Output Feedback Control

We demonstrate for the first time the effectiveness of output feedback controllers previously designed for the Ginzburg-Landau model in attenuating vortex shedding in an actual flow past a 2-D cylinder. The actual flow is represented by a full-blown computational fluid dynamics (CFD) solver, from which measurements are restricted to the cylinder surface, co-located with actuation. Actuation is performed by rotation of the cylinder, and the sensed quantity is the shear at the downstream end of the cylinder. The observer-based controller successfully attenuates vortex shedding, stabilizes the flow, and eliminates lift force oscillations. CFD simulation flow fields are examined in detail, revealing the basic mechanism of the controller and providing an intuitive explanation as to why it works.