Recursive dynamic mode decomposition of transient and post-transient wake flows
File(s)RDMD_revised.pdf (13.39 MB)
Accepted version
Author(s)
Noack, BR
Stankiewicz, W
Morzyński, M
Schmid, PJ
Type
Journal Article
Abstract
A novel data-driven modal decomposition of fluid flow is proposed, comprising key features of proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD). The first mode is the normalized real or imaginary part of the DMD mode that minimizes the time-averaged residual. The NNth mode is defined recursively in an analogous manner based on the residual of an expansion using the first N−1N−1 modes. The resulting recursive DMD (RDMD) modes are orthogonal by construction, retain pure frequency content and aim at low residual. Recursive DMD is applied to transient cylinder wake data and is benchmarked against POD and optimized DMD (Chen et al., J. Nonlinear Sci., vol. 22, 2012, pp. 887–915) for the same snapshot sequence. Unlike POD modes, RDMD structures are shown to have purer frequency content while retaining a residual of comparable order to POD. In contrast to DMD, with exponentially growing or decaying oscillatory amplitudes, RDMD clearly identifies initial, maximum and final fluctuation levels. Intriguingly, RDMD outperforms both POD and DMD in the limit-cycle resolution from the same snapshots. Robustness of these observations is demonstrated for other parameters of the cylinder wake and for a more complex wake behind three rotating cylinders. Recursive DMD is proposed as an attractive alternative to POD and DMD for empirical Galerkin models, in particular for nonlinear transient dynamics.
Date Issued
2016-11-21
Date Acceptance
2016-10-19
Citation
Journal of Fluid Mechanics, 2016, 809, pp.843-872
ISSN
1469-7645
Publisher
Cambridge University Press
Start Page
843
End Page
872
Journal / Book Title
Journal of Fluid Mechanics
Volume
809
Copyright Statement
© 2016 Cambridge University Press. This paper has been accepted for publication and will appear in a revised form, subsequent to peer-review and/or editorial input by Cambridge University Press. Journal of Fluid Mechanics https://www.cambridge.org/core/journals/journal-of-fluid-mechanics
Subjects
Fluids & Plasmas
01 Mathematical Sciences
09 Engineering
Publication Status
Published