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Journal article
Permuted proper orthogonal decomposition for analysis of advecting structures
Journal of fluid mechanics, Vol.930
11/11/2021
Handle:
https://hdl.handle.net/2376/118526
Appears in Aviation Sustainability Center (ASCENT)
Abstract
Flow data are often decomposed using proper orthogonal decomposition (POD) of the space-time separated form, q' (x, t) = Sigma(j) a(j) (t) phi(j) (x), which targets spatially correlated flow structures in an optimal manner. This paper analyses permuted POD (PPOD), which decomposes data as q' (x, t) = Sigma(j) a(j) (n) phi(j) (s, t), where x = (s, n) is a general spatial coordinate system, s is the coordinate along the bulk advection direction and n = (n(1), n(2)) are along mutually orthogonal directions normal to the advection characteristic. This separation of variables is associated with a fundamentally different inner product space for which PPOD is optimal and targets correlations in s, t space. This paper presents mathematical features of PPOD, followed by analysis of three experimental datasets from high-Reynolds-number, turbulent shear flows: a wake, a swirling annular jet and a jet in cross-flow. In the wake and swirling jet cases, the leading PPOD and space-only POD modes focus on similar features but differ in convergence rates and fidelity in capturing spatial and temporal information. In contrast, the leading PPOD and space-only POD modes for the jet in cross-flow capture completely different features - advecting shear layer structures and flapping of the jet column, respectively. This example demonstrates how the different inner product spaces, which order the PPOD and space-only POD modes according to different measures of variance, provide unique 'lenses' into features of advection-dominated flows, allowing complementary insights.
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Details
- Title
- Permuted proper orthogonal decomposition for analysis of advecting structures
- Creators
- Hanna M. Ek - Georgia Institute of TechnologyVedanth Nair - Supreme Council Of HealthChristopher M. Douglas - Supreme Council Of HealthTimothy C. Lieuwen - Supreme Council Of HealthBenjamin L. Emerson - Georgia Institute of Technology
- Publication Details
- Journal of fluid mechanics, Vol.930
- Academic Unit
- Aviation Sustainability Center (ASCENT); Alternative Jet Fuel
- Publisher
- Cambridge Univ Press
- Number of pages
- 30
- Grants
- 13-C-AJFF-GIT-008, Federal Aviation Administration (United States, Washington) - FAA1705649, U.S. National Science Foundation (United States, Alexandria) - NSFFA9550-20-1-0215, United States Air Force Office of Scientific Research (United States, Arlington) - AFOSR
- Grant note
- 13-C-AJFE-GIT-008 / FAA Center of Excellence for Alternative Jet Fuels and the Environment 1705649 / National Science Foundation; National Science Foundation (NSF) FA9550-20-1-0215 / Air Force Office of Scientific Research; United States Department of Defense; Air Force Office of Scientific Research (AFOSR)
- Identifiers
- 99900898128401842
- Language
- English
- Resource Type
- Journal article