Free-surface flow measurements by non-intrusive methods: a survey

Gomit, Guillaume; Chatellier, Ludovic; Lee, David

doi:10.1007/s00348-022-03450-5

Cited by 19 publications

(13 citation statements)

References 78 publications

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“…Flows that can be accurately captured in two dimensions by a single camera do not necessarily require photogrammetric analysis methods but can often be adequately analyzed by simpler optical methods such as edge detection, thresholding for grayscale, and other well-established image transformation methods. Recent reviews of optical methods for measuring the topography of free-surface flows were published in [ 74 , 75 ]. Bung [ 17 ] used a high-speed camera to study the air–water surface topography of a stepped spillway model, where the spillway walls were transparent to reveal the flow cross-section.…”

Section: Methods For Measuring Free Water Surfacementioning

confidence: 99%

“…The authors simultaneously measured the mean surface height of the fluid and the wave velocity using digital image correlation (DIC). As noted in [ 75 ], optical methods based on particle seeding and/or submerged 2D calibration targets with patterns perform best when vertical amplitude of the fluctuations at the fluid surface was small compared to the planar dimension of the fluid mass, and there are few or no air pockets.…”

Section: Methods For Measuring Free Water Surfacementioning

confidence: 99%

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A Review on Methods for Measurement of Free Water Surface

Rak

Hočevar

Repinc

et al. 2023

Sensors

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Turbulent free-surface flows are encountered in several engineering applications and are typically characterized by the entrainment of air bubbles due to intense mixing and surface deformation. The resulting complex multiphase structure of the air–water interface presents a challenge in precise and reliable measurements of the free-water-surface topography. Conventional methods by manometers, wave probes, point gauges or electromagnetic/ultrasonic devices are proven and reliable, but also time-consuming, with limited accuracy and are mostly intrusive. Accurate spatial and temporal measurements of complex three-dimensional free-surface flows in natural and man-made hydraulic structures are only viable by high-resolution non-contact methods, namely, LIDAR-based laser scanning, photogrammetric reconstruction from cameras with overlapping field of view, or laser triangulation that combines laser ranging with high-speed imaging data. In the absence of seeding particles and optical calibration targets, sufficient flow aeration is essential for the operation of both laser- and photogrammetry-based methods, with local aeration properties significantly affecting the measurement uncertainty of laser-based methods.

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Section: Methods For Measuring Free Water Surfacementioning

confidence: 99%

Section: Methods For Measuring Free Water Surfacementioning

confidence: 99%

A Review on Methods for Measurement of Free Water Surface

Rak

Hočevar

Repinc

et al. 2023

Sensors

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“…The physical quantities relevant to describe the process can be acquired with high accuracy in the laboratory via advanced and sophisticated measuring techniques. In particular, the advances in measuring techniques in the last two decades, especially the non-intrusive ones, have considerably enlarged the types of data that can be collected, and have improved their accuracy (e.g., [2][3][4]). Conversely, recovering reliable and accurate validation data from historical documents on real dam-breaks is unlikely because such catastrophic events are, fortunately, rare and seldom well documented [5].…”

Section: Introductionmentioning

confidence: 99%

Review of Experimental Investigations of Dam-Break Flows over Fixed Bottom

Aureli

Maranzoni

Petaccia

et al. 2023

Water

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Laboratory experiments of dam-break flows are extensively used in investigations of geophysical flows involving flood waves, to provide insight into relevant aspects of the physics of the process and collect experimental data for validating numerical models. A dam-break flow is a typical example of a highly unsteady free surface flow with high reproducibility. Indeed, dam-break experiments can be repeated several times under the same test conditions obtaining large amounts of different types of data (possibly using various measuring techniques) that can be combined in a single rich dataset. Moreover, laboratory tests on dam-break flows are widely considered a valuable benchmark for the validation of numerical models, since field data from historical events are scarce, sparse, and highly uncertain. However, no systematic review of laboratory investigations of dam-break flows and existing related datasets are available in the literature to provide a comprehensive overview of the test conditions considered, the measuring techniques used, and the experimental data collected. This review article aims to fill this gap, focusing on laboratory tests in schematic and idealized setups with a fixed, non-erodible bed. In particular, this review aims to help researchers and modelers to: (a) select the most appropriate laboratory tests for validating their numerical models; (b) facilitate access to databases by indicating relevant bibliographic references; (c) identify specific challenging aspects worthy of further experimental research; and (d) support the development of new or improved technologies for the mitigation of the impact of dam-break flood waves. The references reviewed are organized into tables according to the purposes of the laboratory investigation, and comprehensive information is provided on test conditions, datasets, and data accessibility. Finally, suggestions for future experimental research on dam-break flows are provided.

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“…The TIR-D and M-G techniques, due to their recency, are featured in limited studies other than the original work (Jain et al, 2022;Jain, Gauthier, Lohse, et al, 2021;Jain, Vega-Martínez, et al, 2021;Kochkin et al, 2022;Mungalov & Derevyannikov, 2021;Rudenko et al, 2022). These techniques have also gone unnoticed in reviews of optical techniques for surface measurements such as a recent comprehensive review by Gomit et al (2022). The novelty of the present work is furthered by making use of a fairly atypical algorithm (Farneback algorithm) in the context of free surface reconstruction.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Schlieren-based techniques for measurements of a turbulent and wavy free surface

Bheeroo

Mandel

2023

Preprint

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The free surface at an air-water interface can provide information regarding bathymetric complexities, as well as the subsurface flow. We present a comparison of the performance of two recent advances in light-based optical techniques for free surface measurements, Total Internal Reflection-Deflectometry and Moon-Glade Background Oriented Schlieren, with the more established method of Free-Surface Synthetic Schlieren. We make use of an optical flow algorithm over the more traditional Digital Image Correlation, in order to obtain higher spatial resolution data across the imaged free surface domain. The Optical flow algorithm presents additional benefits, such as computational efficiency and robustness in capturing large displacements and straining of tracked features. The three optical techniques are assembled in synchronization to image two free surface conditions: (1) a free surface being impinged upon by an underlying turbulent, free-shear flow and (2) a random and irregular wave field induced by a free jet. Using the high-resolution measurements, we provide insight on the emergence of multiple free surface dynamics for a turbulent free surface and dissect the local hydrodynamics of the free surface for several wave forcings. We present a comprehensive discussion on the benefits and drawbacks of each technique, including suggestions on the suitability of each technique for several experimental constraints.

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Free-surface flow measurements by non-intrusive methods: a survey

Cited by 19 publications

References 78 publications

A Review on Methods for Measurement of Free Water Surface

A Review on Methods for Measurement of Free Water Surface

Review of Experimental Investigations of Dam-Break Flows over Fixed Bottom

Comparison of Schlieren-based techniques for measurements of a turbulent and wavy free surface

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