Resolvent-based Modelling, Estimation and Control of the Cylinder Wake

We use a resolvent based approach for the modelling, estimation and control of the cylinder wake at Reynolds numbers between $60$ and $120$. The work has three parts. First, we consider the optimal estimation problem in which a single sensor is used to estimate the whole flow field. Second, we consider full-information control in which a single actuator uses knowledge of the entire flow field for control. Third, we consider feedback control with a single sensor for measurement and a single actuator for control. A range of Reynolds numbers is considered and the trends of optimal sensor and actuator placements for estimation and control are presented.