A three-dimensional scanning stereoscopic particle image velocimetry for large-volume liquid flows

Fuente: arXiv
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Main Authors: van der Plas, Paul, He, Yutian, Mathai, Varghese
Format: Preprint
Published: 2025
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author van der Plas, Paul
He, Yutian
Mathai, Varghese
author_facet van der Plas, Paul
He, Yutian
Mathai, Varghese
contents We introduce a Scanning Stereoscopic Particle Image velocimetry~(SSPIV) system which incorporates a thin rotating prism to obtain three-dimensional velocity fields in a large cubical measurement volume. The system makes use of an arrangement where a laser beam is first laterally deflected using an even-faced prism, and then passed through a cylindrical lens rod to obtain light sheets for illumination. This eliminates the need for large rotating mirrors or heavy prisms and facilitates relatively fast rotation speeds of up to 4800 rpm for the prism, yielding three-dimensional, three-component velocity field over a large depth at relatively high particle seeding density. About $10^6$ velocity vectors (3D-3C) are obtained in a single volumetric-scan of $100 \times 100 \times 100$ mm$^3$. The method is demonstrated using two independent experiments, (1) a round jet at Reynolds number Re = 1000, and (2) the flow field around a freely rising sphere at a Reynolds number Re$_p$ $\approx$ 260, and the wake flow is compared with direct numerical simulations of a falling viscous droplet. The scanning gives time-resolved evolution of the large-scale vortical structures of the Re = 1000 jet, with spatial gradients captured fairly well. The three-dimensional flow field surrounding the refractive-index-matched rising sphere is shown to be steady and non-axisymmetric. The flow field and separation bubble are seen to be similar, but slightly shorter than that of the falling droplet case and the uniform flow past a fixed sphere case at a comparable Reynolds number.
format Preprint
id arxiv_https___arxiv_org_abs_2507_14753
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A three-dimensional scanning stereoscopic particle image velocimetry for large-volume liquid flows
van der Plas, Paul
He, Yutian
Mathai, Varghese
Fluid Dynamics
We introduce a Scanning Stereoscopic Particle Image velocimetry~(SSPIV) system which incorporates a thin rotating prism to obtain three-dimensional velocity fields in a large cubical measurement volume. The system makes use of an arrangement where a laser beam is first laterally deflected using an even-faced prism, and then passed through a cylindrical lens rod to obtain light sheets for illumination. This eliminates the need for large rotating mirrors or heavy prisms and facilitates relatively fast rotation speeds of up to 4800 rpm for the prism, yielding three-dimensional, three-component velocity field over a large depth at relatively high particle seeding density. About $10^6$ velocity vectors (3D-3C) are obtained in a single volumetric-scan of $100 \times 100 \times 100$ mm$^3$. The method is demonstrated using two independent experiments, (1) a round jet at Reynolds number Re = 1000, and (2) the flow field around a freely rising sphere at a Reynolds number Re$_p$ $\approx$ 260, and the wake flow is compared with direct numerical simulations of a falling viscous droplet. The scanning gives time-resolved evolution of the large-scale vortical structures of the Re = 1000 jet, with spatial gradients captured fairly well. The three-dimensional flow field surrounding the refractive-index-matched rising sphere is shown to be steady and non-axisymmetric. The flow field and separation bubble are seen to be similar, but slightly shorter than that of the falling droplet case and the uniform flow past a fixed sphere case at a comparable Reynolds number.
title A three-dimensional scanning stereoscopic particle image velocimetry for large-volume liquid flows
topic Fluid Dynamics
url https://arxiv.org/abs/2507.14753