A critical comparison of Lagrangian methods for coherent structure detection.
- Hadjighasem A Department of Mechanical Engineering, MIT, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA.
- Farazmand M Department of Mechanical Engineering, MIT, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA.
- Blazevski D Insight Data Science, 45W 25th St., New York, New York 10010, USA.
- Froyland G School of Mathematics and Statistics, University of New South Wales, Sydney, NSW 2052, Australia.
- Haller G Department of Mechanical and Process Engineering, Institute of Mechanical Systems, ETH Zürich, Leonhardstrasse 21, 8092 Zürich, Switzerland.
- 2017-06-04
Published in:
- Chaos (Woodbury, N.Y.). - 2017
English
We review and test twelve different approaches to the detection of finite-time coherent material structures in two-dimensional, temporally aperiodic flows. We consider both mathematical methods and diagnostic scalar fields, comparing their performance on three benchmark examples: the quasiperiodically forced Bickley jet, a two-dimensional turbulence simulation, and an observational wind velocity field from Jupiter's atmosphere. A close inspection of the results reveals that the various methods often produce very different predictions for coherent structures, once they are evaluated beyond heuristic visual assessment. As we find by passive advection of the coherent set candidates, false positives and negatives can be produced even by some of the mathematically justified methods due to the ineffectiveness of their underlying coherence principles in certain flow configurations. We summarize the inferred strengths and weaknesses of each method, and make general recommendations for minimal self-consistency requirements that any Lagrangian coherence detection technique should satisfy.
- Language
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- English
- Open access status
- green
- Identifiers
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- DOI 10.1063/1.4982720
- PMID 28576102
- Persistent URL
- https://folia.unifr.ch/global/documents/250366
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