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