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arXiv · 2402.15954

Forward and inverse modeling of depth-of-field effects in background-oriented schlieren

Joseph P. Molnar·Elijah J. LaLonde·Christopher S. Combs·Olivier Léon·David Donjat·Samuel J. Grauer
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Abstract

We report a novel "cone-ray" model of background-oriented schlieren (BOS) imaging that accounts for depth-of-field effects. Reconstructions of the density field performed with this model are far more robust to the blur associated with a finite aperture than conventional reconstructions, which presume a "thin-ray" pinhole camera. Our model is characterized and validated using forward evaluations based on simulated and experimental BOS measurements of buoyancy-driven flow and hypersonic flow over a sphere. Moreover, we embed the model in a neural reconstruction algorithm, which is demonstrated with a total variation penalty as well as the compressible Euler equations. Our cone-ray technique dramatically improves the accuracy of BOS reconstructions: the shock interface is well-resolved in all our tests, irrespective of the camera's aperture setting, which spans f-numbers from 22 down to 4.

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Joseph P. Molnar, Elijah J. LaLonde, Christopher S. Combs, Olivier Léon, David Donjat, Samuel J. Grauer. 2024-02-25. Forward and inverse modeling of depth-of-field effects in background-oriented schlieren. https://doi.org/10.2514/1.j064095

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