Abstract
We present a comparative analysis of proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) computed from experimental data of a turbulent, quasi 2-D, confined jet with co-flow (Re = 11,500, co-flow ratio inner-to-outer flow ≈2:1). The experimental data come from high-speed 2-D particle image velocimetry. The flow is fully turbulent, and it contains geometry-dependent large-scale coherent structures; thus, it provides an interesting benchmark case for the comparison between POD and DMD. In this work, we address issues related to snapshot selections (1), convergence (2) and the physical interpretation (3) of both POD and DMD modes. We found that the convergence of POD modes follows the criteria of statistical convergence of the autocovariance matrix. For the computation of DMD modes, we suggest a methodology based on two criteria: the analysis of the residuals to optimize the sampling parameters of the snapshots, and a time-shifting procedure that allows us to identify the spurious modes and retain the modes that consistently appear in the spectrum. These modes are found to be the ones with nearly null growth rate. We then present the selected modes, and we discuss the way POD and DMD rank them. POD analysis reveals that the most energetic spatial structures are related to the large-scale oscillation of the inner jet (flapping); from the temporal analysis emerges that these modes are associated with a low-frequency peak at St = 0.02. At this frequency, DMD identifies a similar mode, where oblique structures from the walls appear together with the flapping mode. The second most energetic group of modes identified is associated with shear-layer oscillations, and to a recirculation zone near the inner jet. Temporal analysis of these modes shows that the flapping of the inner jet might be sustained by the recirculation. In the DMD, the shear-layer modes are separated from the recirculation modes. These have large amplitudes in the DMD. In conclusion, the DMD modes with eigenvalues on the unit circle are found to be similar to the most energetic POD modes, although differences appear due to the fact that DMD isolates structures associated with one frequency only.
Similar content being viewed by others
References
Aubry N (1991) On the hidden beauty of the proper orthogonal decomposition. Theoret Comput Fluid Dyn 2:339–352
Bagheri S (2010) Analysis and control of transitional shear layers using global modes. PhD thesis, KTH Mechanics, Sweden
Bendat JS, Piersol AG (2010) Random data: Analysis and measurement procedures. Wiley, Hoboken
Chen K, Tu J, Rowley C (2012) Variants of dynamic mode decomposition: boundary condition, Koopman, and Fourier Analyses. J Nonlinear Sci. doi:10.1007/s00332-012-9130-9
Chua L, Lua A (1998) Measurements of a confined jet. Phys Fluids 10:3137
Goldschmidt V, Bradshaw P (1973) Flapping of a plane jet. Phys Fluids 16:354–355
Holmes P, Lumley J, Berkooz G (1996) Turbulence coherent structures, dynamical systems and symmetry. Cambridge University Press, Cambridge
Ilak M, Rowley CW (2008) Modeling of transitional channel flow using balanced proper orthogonal decomposition. Phys Fluids 20:034103
Kolmogorov A (1941) The local structure of turbulence in incompressible viscous fluid for very large reynolds numbers. Dokl Akad Nauk SSSR 30:299–303
Lawson NJ, Davidson MR (2001) Self-sustained oscillation of a submerged jet in a thin rectangular cavity. J Fluids Struct 15(1):59–81. doi:10.1006/jfls.2000.0327
Loève M (1945) Functions alèatorie de second ordre. Comptes Rendus Acad Sci, Paris, p 220
Lumley JL (1970) Stochastic tools in turbulence. Academic Press, New York
Maurel A, Ern P, Zielinska B, Wesfreid J (1996) Experimental study of self-sustained oscillations in a confined jet. Phys Rev E 54(4):3643–3651
Mezić I (2005) Spectral properties of dynamical systems, model reduction and decompositions. Nonlinear Dyn 41(1):309–325
Noack B, Afanasiev K, Morzynski M, Tadmor G, Thiele F (2003) A hierarchy of low-dimensional models for the transient and post-transient cylinder wake. J Fluid Mech 497:335–363
Noack B, Schlegel B, Ahlborn B, Mutschke G, Norzynski M, Comte P, Tadmor G (2008) A finite-time thermodynamics formalism for unsteady flows. J Non-Equilib Thermodyn 33:103–148
Omurtag A, Sirovich L (1999) On low-dimensional modeling of channel turbulence. Theoret Comput Fluid Dyn 13:115–127
Örlu R, Segalini A, Alfredsson P, Talamelli A (2008) On the passive control of the near-field of coaxial jets by means of vortex shedding. International Conference on Jets, Wakes and Separated Flows, ICJWSF-2008 September 16–19, 2008, Technical University of Berlin, Berlin
Poelma C, Westerweel J, Ooms G (2006) Turbulence statistics from optical whole-field measurements in particle-laden turbulence. Exp Fluids 40:347–363
Raffel M, Willert CE, Kompenhans J (1998) Particle image velocimetry: a practical guide. Springer, Berlin
Rempfer D, Fasel H (1994) Evolution of three-dimensional coherent structures in a flat-plate boundary layer. J Fluid Mech 260:351–375
Rowley CW, Mezic I, Bagheri S, Schlatter P, Henningson DS (2009) Spectral analysis of nonlinear flows. J Fluid Mech 641:115–127
Ruhe A (1984) Rational Krylov sequence methods for eigenvalue computation. Linear Algebra Appl 58:391–405
Schmid PJ (2010) Dynamic mode decomposition. J Fluid Mech 656:5–28
Schmid PJ, Violato D, Scarano F (2012) Decomposition of time-resolved tomographic PIV. Exp Fluids. 52(6):1567–1579. doi:10.1007/s00348-012-1266-8
Sirovich L (1987) Turbulence and the dynamics of coherent structures I-III. Q Appl Math 45:561–590
Stanislas M, Okamoto K, Kähler C, Westerweel J (2008) Main results of the third international PIV challenge. Exp Fluids 45:27–71
Tinney C, Jordan P (2008) The near pressure field of co-axial subsonic jets. J Fluid Mech 611:175–204. doi:10.1017/S0022112008001833
Tsinober A (2004) An informal introduction to turbulence. Kluwer, Berlin
Willert C (2006) Assessment of camera models for use in planar velocimetry calibration. Exp Fluids 41:135–143
Acknowledgments
Gabriele Bellani and Fredrik Lundell thank the Swedish energy agency for funding. Computer time was provided by SNIC (Swedish National Infrastructure for Computing). We also wish to acknowledge the following persons: Prof. Hiroshi Higuchi for helpful discussion on the design and development of the experimental setup, as well as comments on the analysis of the experimental results; Dr. Ramis Örlü for helpful comments and suggestions on the manuscript; Dr. Shervin Bagheri, Dr. Francesco Picano and Dr. Johan Malm for fruitful discussions.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Semeraro, O., Bellani, G. & Lundell, F. Analysis of time-resolved PIV measurements of a confined turbulent jet using POD and Koopman modes. Exp Fluids 53, 1203–1220 (2012). https://doi.org/10.1007/s00348-012-1354-9
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00348-012-1354-9