Flow separation reduces aerodynamic performance and can increase unsteady loading and noise. This seminar describes an adaptive feedback-control approach that uses online dynamic mode decomposition (DMD) to identify the changing dynamics of a separated laminar boundary layer during control. In the experiment, a pulse-modulated, zero-net-mass-flux jet located just upstream of separation provides actuation, while thirteen flush-mounted microphones measure the flow response. Online DMD extracts a reduced-order model from the measurements and updates it continuously, without requiring prior identification of the uncontrolled flow.
Louis N. Cattafesta III,
Illinois Institute of Technology
The resulting model is used to recompute the gains of a linear quadratic regulator as the flow evolves. Experiments over four Reynolds numbers, from 0.9 × 10⁵ to 1.25 × 10⁵, demonstrate effective suppression of the separation bubble and robust performance across operating conditions. Relative to comparable open-loop forcing, adaptive feedback requires approximately 30% less actuator effort. The controlled flow reaches its new state in approximately ten characteristic flow time scales. These results demonstrate the potential of combining real-time, data-driven modeling with established feedback-control methods to improve flow-control efficiency. The seminar will describe the experimental approach, online model identification, and the opportunities and challenges of extending this strategy to more complex separated flows.
Louis N. Cattafesta III is Professor of Engineering and Special Adviser to the Provost for Research Lab Transformation at Illinois Institute of Technology. He previously served as Dean of the Armour College of Engineering (2025–2026) and as department chair (2022–2025). Before joining Illinois Tech, he was a University Eminent Scholar at Florida State University and a professor at the University of Florida. He began his career as a research scientist at NASA Langley Research Center. He earned a B.S. and Ph.D. in mechanical engineering from Penn State and an M.S. in aeronautics from MIT. His research interests include active and passive flow control, aeroacoustics, and experimental methods for unsteady flows. He has coauthored more than 100 journal articles, holds seven U.S. patents, and is a Fellow of AIAA, ASME, APS, and the Royal Aeronautical Society. He serves as an Associate Editor of Experiments in Fluids.