A Nonlinear Dynamical Modeling and Control Method for the Vorticity Control of the Flow past a Circular Cylinder

摘要

In this paper a systematic approach for the nonlinear modeling and feedback control of vorticity behind an immersed circular cylinder system was developed. In this technique first a number of control input points over the cylinder and some measurement points for vorticity past the cylinder are assigned. A type of nonlinear dynamic model (namely a Hammerstein-Wiener (HW) model) of the flow field is estimated via system identification techniques using measurement data obtained from a chirp input function. Once the dynamical model of the system is estimated, a controller for the linear block of the HW model is designed using internal model control method, and this controller is then mapped to the HW model by reversing the input/output nonlinearity functions. The procedure described is implemented and tested numerically in MATLAB and CFD computations performed on the closed-loop system show that the controller is capable of achieving significant reduction in the vorticity levels past the cylinder.