Journal ArticleDOI
Feedback shear layer control for bluff body drag reduction
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TLDR
In this paper, a reduced-order vortex model describes the interaction between the shear layer and wake dynamics and guides a path to an efficient feedback control design for the turbulent flow around a D-shaped body.Abstract:
Drag reduction strategies for the turbulent flow around a D-shaped body are examined experimentally and theoretically. A reduced-order vortex model describes the interaction between the shear layer and wake dynamics and guides a path to an efficient feedback control design. The derived feedback controller desynchronizes shear-layer and wake dynamics, thus postponing vortex formation. This actuation is tested in a wind tunnel. The Reynolds number based on the height of the body ranges from 23000 to 70000. We achieve a 40% increase in base pressure associated with a 15% drag reduction employing zero-net-mass-flux actuation. Our controller outperforms other approaches based on open-loop forcing and extremum-seeking feedback strategies in terms of drag reduction, adaptivity, and the required actuation energy.read more
Citations
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On Dynamic Mode Decomposition: Theory and Applications
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Closed-Loop Turbulence Control: Progress and Challenges
Steven L. Brunton,Bernd R. Noack +1 more
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Cluster-based reduced-order modelling of a mixing layer
Eurika Kaiser,Bernd R. Noack,Laurent Cordier,Andreas Spohn,Marc Segond,Markus Abel,Guillaume Daviller,Jan Östh,Sinisa Krajnovic,Robert K. Niven +9 more
TL;DR: In this article, the authors proposed a cluster-based reduced-order modeling (CROM) strategy for unsteady flows, which combines the cluster analysis pioneered in Gunzburger's group and transition matrix models introduced in Eckhardt's group to identify non-trivial quasi-attractors and transition processes in an unsupervised manner.
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Machine Learning Control – Taming Nonlinear Dynamics and Turbulence
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On the need for a nonlinear subscale turbulence term in POD models as exemplified for a high-Reynolds-number flow over an Ahmed body
TL;DR: In this paper, a hierarchy of eddy-viscosity terms in proper orthogonal decomposition (POD) Galerkin models is investigated to account for a large fraction of unresolved fluctuation energy.
References
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Applied Optimal Estimation
TL;DR: This is the first book on the optimal estimation that places its major emphasis on practical applications, treating the subject more from an engineering than a mathematical orientation, and the theory and practice of optimal estimation is presented.
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Brief Stability of extremum seeking feedback for general nonlinear dynamic systems
Miroslav Krstic,Hsin-Hsiung Wang +1 more
TL;DR: This paper provides the first proof of stability of an extremum seeking feedback scheme by employing the tools of averaging and singular perturbation analysis and allows the plant to be a general nonlinear dynamic system whose reference-to-output equilibrium map has a maximum and whose equilibria are locally exponentially stabilizable.
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