Control of cavity-driven separated boundary layer

Authors: Hoepffner, J.P.J., Åkervik, E.Å., Ehrenstein, U, Henningson, D.S.H.
Document Type: Conference
Pubstate: Accepted
Journal: Proceedings of the Conference on active flow control, Berlin, September 2006.
Year: 2006


The aim of this paper is to use the eigenmodes of the 2D flow, first to analyse its dynamics, and second to build a reduced model for control design. The cavity driven separated boundary layer presents similarities with the flat plate boundary layer separation bubble, but with fixed separation and reatachment points. The flow dynamics is dominated by the shear layer instability, and the pressure is found to play a coupling role between separation and reatachment, potentially leading to global instability. The structure of the computed eigenmodes is discussed in details. The large dimensionality of the discretized flow system is a challenge for control design. A reduced dynamic model is constructed by projection on a basis of eigenmodes, and the controller optimized for this reduced model is found to perform well on the full system.