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Active Control of Flow Over a Backward-Facing Step

We describe a control-oriented model reduction process from partial differential equation (PDE) descriptions of aerodynamic flow systems, and the design of low-order feedback controllers using these procedures. An effective approach for flow model reduction for active control using balanced truncation approaches was developed. The techniques were applied to a flow control problem representative of aerospace problems: active control of flow over a modified 2D backward-facing step, which can be handled by most commercial finite element packages. Although the geometry is rather simple, the richness of the flow field is well documented. Feedback controllers were developed for disturbance rejection and tracking of the reattachment point for both high and low Reynolds numbers.