Adaptive and model-based control theory applied to convectively unstable flows

Authors: Fabbiane, N., Semeraro, O., Bagheri, S., Henningson, D.S.H.
Document Type: Article
Pubstate: Published
Journal: Appl. Mech. Reviews
Volume: 66(6)   060801
Year: 2014


Research on active control for the delay of laminar-turbulent transition in boundary layers has made a significant progress in the last two decades, but the employed strategies have been many and dispersed. Using one framework, we review model-based techniques, such as linear-quadratic regulators, and model-free adaptive methods, such as least-mean square filters. The former are supported by a elegant and powerful theoretical basis, whereas the latter may provide a more practical approach in the presence of complex disturbance environments, that are difficult to model. We compare the methods with a particular focus on efficiency, practicability and robustness to uncertainties. Each step is exemplified on the one-dimensional linearized Kuramoto-Sivashinsky equation, that shows many similarities with the initial linear stages of the transition process of the flow over a flat plate. Also, the source code for the examples are provided.