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Article

Towards Reconstruction of Complex Flow Fields Using Unit Flows

1
Mechanical Engineering Department, Texas A&M University, College Station, TX 77840, USA
2
Nuclear Engineering Department, Texas A&M University, College Station, TX 77843, USA
3
Ocean Engineering Department, Texas A&M University, College Station, TX 77843, USA
*
Author to whom correspondence should be addressed.
Academic Editor: Omer San
Fluids 2021, 6(7), 255; https://doi.org/10.3390/fluids6070255
Received: 8 May 2021 / Revised: 25 June 2021 / Accepted: 5 July 2021 / Published: 13 July 2021
(This article belongs to the Special Issue Scientific Computing in Fluids)
Many complex turbulent flows in nature and engineering can be qualitatively regarded as being constituted of multiple simpler unit flows. The objective of this work is to characterize the coherent structures in such complex flows as a combination of constituent unitary flow structures for the purpose of reduced-order representation. While turbulence is clearly a non-linear phenomenon, we aim to establish the degree to which the optimally weighted superposition of unitary flow structures can represent the complex flow structures. The rationale for investigating such superposition stems from the fact that the large-scale coherent structures are generated by underlying flow instabilities that may be reasonably described using linear analysis. Clearly, the degree of validity of superposition will depend on the flow under consideration. In this work, we take the first step toward establishing a procedure for investigating superposition. Experimental data of single and triple tandem jets in crossflow are used to demonstrate the procedure. A composite triple tandem jet flow field is generated from optimal superposition of single jet data and compared against ‘true’ triple jet data. Direct comparisons between the true and composite fields are made for spatial, temporal, and kinetic energy content. The large-scale features (obtained from proper orthogonal decomposition or POD) of true and composite tandem jet wakes exhibit nearly 70% agreement in terms of modal eigenvector correlation. Corresponding eigenvalues reveal that the kinetic energy of the flow is also emulated with only a slight overprediction. Temporal frequency features are also examined in an effort to completely characterize POD modes. The proposed method serves as a foundation for more rigorous and robust dimensional reduction in complex flows based on unit flow modes. View Full-Text
Keywords: complex flow; data driven; flow reconstruction; linear filters; proper orthogonal decomposition (POD); superposition; unit flow complex flow; data driven; flow reconstruction; linear filters; proper orthogonal decomposition (POD); superposition; unit flow
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MDPI and ACS Style

Kristo, P.J.; Kimber, M.L.; Girimaji, S.S. Towards Reconstruction of Complex Flow Fields Using Unit Flows. Fluids 2021, 6, 255. https://doi.org/10.3390/fluids6070255

AMA Style

Kristo PJ, Kimber ML, Girimaji SS. Towards Reconstruction of Complex Flow Fields Using Unit Flows. Fluids. 2021; 6(7):255. https://doi.org/10.3390/fluids6070255

Chicago/Turabian Style

Kristo, Paul J., Mark L. Kimber, and Sharath S. Girimaji 2021. "Towards Reconstruction of Complex Flow Fields Using Unit Flows" Fluids 6, no. 7: 255. https://doi.org/10.3390/fluids6070255

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