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Simulating schlieren and shadowgraph images from LES data

Luthman, Elizabeth and Cymbalist, Niccolo and Lang, Daniel and Candler, Graham and Dimotakis, Paul (2019) Simulating schlieren and shadowgraph images from LES data. Experiments in Fluids, 60 (8). Art. No. 134. ISSN 0723-4864.

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Geometrical optics ray-tracing is used to derive schlieren and shadowgraph images from large-eddy simulation (LES) data of a jet in supersonic crossflow and to compare with experimental data. Including the components of the optical system that forms the image in the simulation is found to be important. The technique produces images that replicate flow physics more faithfully than straight-line path integration and other techniques, and more efficiently than physical-optics techniques. Applications of these simulated images are demonstrated in supersonic flows. Time-correlated pairs of shadowgraph images taken from the LES using this technique are used in conjunction with an image-correlation velocimetry technique to compare the estimated convection velocity field in the LES to that of experiments of the same flow. Agreement between the two is good with a maximum variance of 5% by some metrics. This technique can aid in the validation of LES results, allowing quantitative comparison between experiment and simulation, and to extract information unattainable by experiment alone. Comparisons of simulated and experimental jet penetration into the supersonic freestream are also made.

Item Type:Article
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Luthman, Elizabeth0000-0003-3225-8877
Additional Information:© 2019 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Received 28 December 2018; Revised 06 July 2019; Accepted 08 July 2019; First Online 26 July 2019. The work was supported by AFOSR Grant FA9550-12-1-0461, and DOE Grant DE-NA0002382. Computations were facilitated by the data-storage/-visualization computer cluster integrated by Daniel Lang and developed through support by NSF MRI Grant EIA-0079871, AFOSR DURIP Grant FA9550-10-1-0553, and support by the AFOSR and DOE grants mentioned above. We would also like to acknowledge discussions with Oscar Bruno, Ross Choudary, Anand Kartha, Pramod Subbareddy, and Erik Tylczak.
Funding AgencyGrant Number
Air Force Office of Scientific Research (AFOSR)FA9550-12-1-0461
Department of Energy (DOE)DE-NA0002382
Air Force Office of Scientific Research (AFOSR)FA9550-10-1-0553
Issue or Number:8
Record Number:CaltechAUTHORS:20190726-104616679
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Official Citation:Luthman, E., Cymbalist, N., Lang, D. et al. Exp Fluids (2019) 60: 134.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97444
Deposited By: Tony Diaz
Deposited On:26 Jul 2019 17:52
Last Modified:03 Oct 2019 21:31

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