Document Type
Article
Publication Date
2-10-2025
Abstract
Optical flow methods have been developed over the past two decades for application to particle image velocimetry (PIV) images with the goal of acquiring higher resolution measurements of the velocity field than conventional cross-correlation (CC)-based techniques. Numerous optical flow velocimetry (OFV) algorithms have been devised to solve the ill-posed optical flow problem, with various physics-inspired strategies to tailor them to fluid flows. While OFV can be applied to continuous scalar fields, it has demonstrated the most success on images of tracer particles, i.e. traditional planar PIV images. Compared to state-of-the-art CC algorithms, OFV methods have demonstrated an order of magnitude increase in spatial resolution and up to a factor of two improvement in overall accuracy when evaluated on synthetic data, at the cost of increased computational time. The requirements for particle seeding density, inter-frame displacement, and image quality are also more stringent for OFV methods compared to CC. OFV has been applied sparingly in experiments to date, but appears to offer the same advantages demonstrated on synthetic data. At this stage, OFV seems best suited to planar velocity measurements, although extensions to stereoscopic measurements have been demonstrated.
Keywords
optical flow, PIV, velocimetry
Language
English
Publication Title
Measurement Science and Technology
Grant
CBET-2306815
Rights
© 2025 The Author(s). This is an Open Access work distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Jassal, G. R., & Schmidt, B. (2025). A review of optical flow velocimetry in fluid mechanics. Measurement Science and Technology.
Manuscript Version
Final Publisher Version