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Assessment and application of optical flow in background-oriented schlieren for compressible flows

Cakir, Bora O. LU orcid ; Lavagnoli, Sergio ; Saracoglu, Bayindir H. and Fureby, Christer LU (2023) In Experiments in Fluids 64(1).
Abstract

Abstract: Optical flow provides an opportunity to elevate the resolution and sensitivity of deflection sensing in background-oriented schlieren (BOS). Despite extensive relevant literature within the field of computer vision, there is a lack of proper quantification of its abilities and limitations with regard to the state-of-the-art BOS experiments. Thus, this study performs an assessment of accuracy and resolution limits in different flow field scenarios utilizing background patterns generated with random dot and wavelet noise distributions. Accordingly, a synthetic assessment over a theoretically generated Prandtl–Meyer expansion fan is conducted with variations introduced in the background patterns and operational parameters of... (More)

Abstract: Optical flow provides an opportunity to elevate the resolution and sensitivity of deflection sensing in background-oriented schlieren (BOS). Despite extensive relevant literature within the field of computer vision, there is a lack of proper quantification of its abilities and limitations with regard to the state-of-the-art BOS experiments. Thus, this study performs an assessment of accuracy and resolution limits in different flow field scenarios utilizing background patterns generated with random dot and wavelet noise distributions. Accordingly, a synthetic assessment over a theoretically generated Prandtl–Meyer expansion fan is conducted with variations introduced in the background patterns and operational parameters of optical flow. A clear superiority of accuracy and resolvable range of density gradient amplitudes over cross-correlation is demonstrated. Moreover, an experimental assessment of supersonic flow features over multiple wind tunnel models is performed. The influence of experimental constraints, limitations and uncertainties related to the application of optical flow in BOS and its comparative performance against the block-matching counterpart is characterized. Graphical abstract: [Figure not available: see fulltext.].

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Experiments in Fluids
volume
64
issue
1
article number
11
publisher
Springer
external identifiers
  • scopus:85145355708
ISSN
0723-4864
DOI
10.1007/s00348-022-03553-z
language
English
LU publication?
yes
id
525658b8-f091-49ce-b1c1-ad8ad1b6c361
date added to LUP
2023-02-13 15:33:13
date last changed
2023-11-07 02:30:18
@article{525658b8-f091-49ce-b1c1-ad8ad1b6c361,
  abstract     = {{<p>Abstract: Optical flow provides an opportunity to elevate the resolution and sensitivity of deflection sensing in background-oriented schlieren (BOS). Despite extensive relevant literature within the field of computer vision, there is a lack of proper quantification of its abilities and limitations with regard to the state-of-the-art BOS experiments. Thus, this study performs an assessment of accuracy and resolution limits in different flow field scenarios utilizing background patterns generated with random dot and wavelet noise distributions. Accordingly, a synthetic assessment over a theoretically generated Prandtl–Meyer expansion fan is conducted with variations introduced in the background patterns and operational parameters of optical flow. A clear superiority of accuracy and resolvable range of density gradient amplitudes over cross-correlation is demonstrated. Moreover, an experimental assessment of supersonic flow features over multiple wind tunnel models is performed. The influence of experimental constraints, limitations and uncertainties related to the application of optical flow in BOS and its comparative performance against the block-matching counterpart is characterized. Graphical abstract: [Figure not available: see fulltext.].</p>}},
  author       = {{Cakir, Bora O. and Lavagnoli, Sergio and Saracoglu, Bayindir H. and Fureby, Christer}},
  issn         = {{0723-4864}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{Springer}},
  series       = {{Experiments in Fluids}},
  title        = {{Assessment and application of optical flow in background-oriented schlieren for compressible flows}},
  url          = {{http://dx.doi.org/10.1007/s00348-022-03553-z}},
  doi          = {{10.1007/s00348-022-03553-z}},
  volume       = {{64}},
  year         = {{2023}},
}