Experimental investigation of internal structure of open-channel flow with intense transport of sediment

Matoušek, Václav; Bareš, Vojtěch; Krupička, Jan; Picek, Tomáš; Zrostlík, Štĕpán

doi:10.1515/johh-2015-0035

Cited by 19 publications

(35 citation statements)

References 15 publications

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“…in the 0.2-m flume in the Water Engineering Laboratory of the Czech Technical University (CTU) in Prague. A detailed description of the setup, measuring equipment and experimental procedure is given elsewhere [6][7][8][9]. For the experiments with bimodal mixtures, the procedure was extended with sieving analyses of samples of transported sediments collected at the outlet of the flume during each test run.…”

Section: Methodsmentioning

confidence: 99%

“…Standard measuring instruments were used to measure integral parameters of the flow (depth, discharge, slope, delivered concentration) and they are described elsewhere [6][7]. We used three different measurement techniques to measure a vertical velocity profile of the longitudinal component of the velocity in the axis of the flume.…”

Section: Measuring Instrumentsmentioning

confidence: 99%

“…The great advantage of ADVP is that it is noninvasive and does not disturb flow in the transport layer. Also velocity measuring instruments are described in more details elsewhere [6][7]9]. An estimation of measuring errors of individual instruments is given in [6].…”

Section: Measuring Instrumentsmentioning

confidence: 99%

“…Also velocity measuring instruments are described in more details elsewhere [6][7]9]. An estimation of measuring errors of individual instruments is given in [6]. Processing of measured data is described in [6][7]9].…”

Section: Measuring Instrumentsmentioning

confidence: 99%

“…An estimation of measuring errors of individual instruments is given in [6]. Processing of measured data is described in [6][7]9]. …”

Section: Measuring Instrumentsmentioning

confidence: 99%

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On the effect of segregation on intense bimodal bed load

Zrostlík

Matoušek

2017

EPJ Web Conf.

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Abstract. Open-channel two-phase flow above a granular mobile bed is studied experimentally and theoretically. In the two-phase flow, water serves as a carrying liquid for plastic grains transported as collisional contact load in the upper-stage plane bed regime. The investigation evaluates friction-and transport characteristics of the flow under the condition of intense collisional transport of grains and links them with the internal structure of the two-phase flow. The paper focusses on the effect of bimodal solids (mixed two fractions of grains of similar density and different size and shape) on the flow characteristics and internal structure. Hence, experimental results obtained for the bimodal mixture are compared with results for individual grain fractions. The experiments show that the bimodal character of the transported solids affects the layered internal structure of the flow as a result of fraction segregation due primarily to gravity (kinetic) sieving during transport. The segregation also affects the friction-and transport characteristics of intense bed load. In the paper, the effects are described and quantified.

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Section: Methodsmentioning

confidence: 99%

Section: Measuring Instrumentsmentioning

confidence: 99%

Section: Measuring Instrumentsmentioning

confidence: 99%

Section: Measuring Instrumentsmentioning

confidence: 99%

“…An estimation of measuring errors of individual instruments is given in [6]. Processing of measured data is described in [6][7]9]. …”

Section: Measuring Instrumentsmentioning

confidence: 99%

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On the effect of segregation on intense bimodal bed load

Zrostlík

Matoušek

2017

EPJ Web Conf.

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Internal structure of intense collisional bedload transport

Matoušek

Zrostlík

Fraccarollo

et al. 2019

Earth Surf Processes Landf

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Intense bed load refers to a regime which is responsible of most of sediment transport in torrents and rivers during floods. Even if restricted to uniform steady conditions and well sorted particles, the liquid and solid phases interact in a rather complex way over the plane mobile bed. We focus on flow conditions where the sediment grains in the flow are supported by mutual contacts, primarily collisions, and not by the fluid turbulence. Nonetheless, the turbulent liquid stresses are important everywhere, but the top of the bed, and may not be neglected. Being particles and fluid reciprocally affecting at various scale, mechanical interpretations are challenging and not consolidated, yet. In this picture, it is clear that experimental evidences provide a fundamental, still lacking, piece of information.We contribute with new experiments in a tilting flume to face this need. Compared to previous laboratory tests, we apply various measuring techniques, getting to a robust validation of the acquired dataset. We exploited stereoscopic imaging techniques to capture the solid concentration and the three components of grain velocity, and extract the velocity fluctuations from the local mean values. Measured velocity distributions are independently checked by using an Ultrasonic Doppler Velocimetry technique.With all the needed quantities available, we exploited the constitutive relations based on the kinetic theory for granular flow, to highlight how the comparison between predictions and measurements works, deploying some accuracy deficiencies in the measurement and/or interpretation limits. Our results also address the attention to interfaces that separate layers affected by different rheological mechanisms. Along with pure experimental and theoretical aspects, we grasp the chance to use the data to check how the relations involving global quantities (discharges, friction factor, bed slope, flow depth), so common in hydraulic practice, work when the sediment transport is intense.

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