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A data-based, reduced-order, dynamic estimator for reconstruction of non-linear flows exhibiting limit-cycle oscillations

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Title: A data-based, reduced-order, dynamic estimator for reconstruction of non-linear flows exhibiting limit-cycle oscillations
Authors: Guzman Inigo, J
Sodar, M
Papadakis, G
Item Type: Journal Article
Abstract: We apply a data-based, linear dynamic estimator to reconstruct the velocity field from measurements at a single sensor point in the wake of an aerofoil. In particular, we consider a NACA0012 aerofoil at Re = 600 and 16◦ angle of attack. Under these conditions, the flow exhibits a vortex shedding limit cycle. A reduced order model (ROM) of the flow field is extracted using proper orthogonal decomposition (POD). Subsequently, a subspace system identification algorithm (N4SID) is applied to extract directly the estimator matrices from the reduced output of the system (the POD coefficients). We explore systematically the effect of the number of states of the estimator, the sensor location, the type of sensor measurements (one or both velocity components), and the number of POD modes to be recovered. When the signal of a single velocity component (in the stream wise or cross stream directions) is measured, the reconstruction of the first two dominant POD modes strongly depends on the sensor location. We explore this behaviour and provide a physical explanation based on the non-linear mode interaction and the spatial distribution of the modes. When however, both components are measured, the performance is very robust, and is almost independent of the sensor location when the optimal number of estimator states is used. Reconstruction of the less energetic modes is more difficult, but still possible. Finally, we assess the robustness of the estimator at off-design conditions, at Re = 550 and 650.`
Issue Date: 21-Nov-2019
Date of Acceptance: 29-Oct-2019
URI: http://hdl.handle.net/10044/1/74329
DOI: 10.1103/PhysRevFluids.4.114703
ISSN: 2469-990X
Publisher: American Physical Society
Journal / Book Title: Physical Review Fluids
Volume: 4
Issue: 11
Copyright Statement: ©2019 American Physical Society.
Keywords: Science & Technology
Physical Sciences
Physics, Fluids & Plasmas
Physics
STOCHASTIC ESTIMATION
SENSOR PLACEMENT
IDENTIFICATION
REDUCTION
physics.flu-dyn
physics.flu-dyn
0102 Applied Mathematics
0203 Classical Physics
0913 Mechanical Engineering
Publication Status: Published
Article Number: ARTN 114703
Appears in Collections:Mechanical Engineering
Aeronautics
Faculty of Engineering