Optimal control of vortex shedding using low-order models. Part I?open-loop model development

Abstract

An approach to developing active control strategies for separated flows is presented. The methodology proposed is applied to the incompressible unsteady wake flow behind a circular cylinder at a Reynold's number of 100. Control action is achieved via cylinder rotation. Low-order models which are amenable to control and which incorporate the full non-linear dynamics are developed by applying the proper orthogonal decomposition technique to data provided by numerical simulation. This process involves extensions to the usual POD approach and the results are therefore assessed for two ‘open-loop’ test cases. The predictions are found to be satisfactory for control purposes, assuming the model can be reset periodically. The use of these models for optimal control is discussed in a companion paper, Part II. Copyright © 1999 John Wiley & Sons, Ltd.