On the resolution limit of digital particle image velocimetry

By Christian J. Kähler, Sven Scharnowski, Christian Cierpka. 2012

287 citations recorded by the source corpus.

This work analyzes the spatial resolution that can be achieved by digital particle image velocimetry (DPIV) as a function of the tracer particles and the imaging and recording system. As the in-plane resolution for window-correlation evaluation is related by the interrogation window size, it was assumed in the past that single-pixel ensemble-correlation increases the spatial resolution up to the pixel limit. However, it is shown that the determining factor limiting the resolution of single-pixel ensemble-correlation are the size of the particle images, which is dependent on the size of the particles, the magnification, the f-number of the imaging system, and the optical aberrations. Furthermore, since the minimum detectable particle image size is determined by the pixel size of the camera sensor in DPIV, this quantity is also considered in this analysis. It is shown that the optimal magnification that results in the best possible spatial resolution can be estimated from the particle size, the lens properties, and the pixel size of the camera. Thus, the information provided in this paper allows for the optimization of the camera and objective lens choices as well as the working distance for a given setup. Furthermore, the possibility of increasing the spatial resolution by means of particle tracking velocimetry (PTV) is discussed in detail. It is shown that this technique allows to increase the spatial resolution to the subpixel limit for averaged flow fields. In addition, PTV evaluation methods do not show bias errors that are typical for correlation-based approaches. Therefore, this technique is best suited for the estimation of velocity profiles.

Subfields: Atomic and Molecular Physics, and Optics, Computational Mechanics, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/d99aa8f94c7cfb2044a5c56aa1d2966f5baff540

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In Atomic and Molecular Physics, and Optics

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Citations in the corpus

Shake-The-Box: Lagrangian particle tracking at high particle image densities (2016, methodology): “The superiority of this approach to correlation-based techniques has been shown in detail for the 2D case (Kähler et al. 2012a, b).”
Higher order multi-frame particle tracking velocimetry (2013, background): “These error levels can easily be reached for elaborate particle detection algorithms and high-quality imaging (Kähler et al. 2012b).”
Particle imaging techniques for volumetric three-component (3D3C) velocity measurements in microfluidics (2011, methodology): “The resolution for correlation methods depends on the particle image diameter and is limited to 29 the particle image diameter (Kähler and Scharnowski, 2011).”
On the uncertainty of digital PIV and PTV near walls (2012, methodology): “Increasing the magnification results in larger particle images and does not gain much spatial resolution in case of correlationbased DPIV evaluation, as discussed in detail in Kähler et al. (2012).”