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New developments in physical hydraulic modeling for sediment transport

Sindelar, Christine, Schobesberger, Johannes, Lichtneger, Petr, Hauer, Christoph, Habersack, Helmut
Österreichische Wasser- und Abfallwirtschaft 2019 v.71 no.3-4 pp. 160-169
algorithms, gravel, hydraulic engineering, models, research projects, sediment transport, tomography, velocimetry
This paper presents new developments in physical modeling of sediment transport based on three specific research projects. New developments in the field of non-invasive laser-optical methods allow to measure spatially and temporally high-resolution 3D velocities in a measuring volume (tomo-PTV = tomographic particle tracking velocimetry). The STB (Shake the Box) algorithm is a further development of the PTV method, which greatly shortens the evaluation time. This is of great value given the large amounts of data in high-resolution measurements. The first project presented in this paper investigates the flow around a single stone using the tomo-PTV method. The coherent structures that were present at the onset of motion—and possibly caused movement—could be measured and visualized. In a second project, flow measurements were coupled with the measurement of moving sediment grains along the rough bed. The results are a contribution to the still open research question as to whether sediment transport increases or decreases bed resistance. As a third project scaling experiments are described which aim to quantify scaling errors in gravel bed rivers. For this purpose, a model family is examined in three different scales. For the 1:1 experiments, the new open-air BOKU research channel was available, which is fed with Danube water and will finally allow flow rates of up to 10 m³/s without pumping. Recent developments in measurement techniques in combination with experimental facilities at or near field scale have the potential to substantially advance the physical process understanding of sediment transport. Based on this, efficient sediment management strategies for hydraulic engineering practice can be developed.