3-Dimensional Laser-Doppler Measurements in a Curved Flume

Booij, R.; Tukker, J.

doi:10.1007/978-3-642-79965-5_7

Cited by 8 publications

(6 citation statements)

References 4 publications

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“…Hence, the crossstream turbulent stresses contribute to the generation as well as the dissipation of the outer-bank cell. Kinetic energy fluxes from the turbulence to the mean flow have been observed in various other experiments in open-channel bends (Anwar 1986;Booij & Tukker 1996;Booij 2003;and Shiono & Muto 1998 for the case of overbank flow in a meander).…”

Section: Interpretation and Modelling Implicationsmentioning

confidence: 71%

“…The bi-cellular pattern of cross-stream circulation has often been observed in curved turbulent flow, in laboratory experiments (Mockmore 1943;Einstein & Harder 1954;Rozovskii 1957;Götz 1975;Choudhary & Narasimhan 1977;Siebert 1982;Booij & Tukker 1996;Shiono & Muto 1998;Tominaga, Nagao & Nezu 1999;Booij 2003), as well as in the field (Bathurst et al 1979;Dietrich & Smith 1983;de Vriend & Geldof 1983). Yet, little is known about the mechanisms underlying it, nor about the conditions for its occurrence.…”

Section: Curved Turbulent Flowmentioning

confidence: 92%

“…Kalkwijk & de Vriend (1980) and Ikeda, Yamasaka & Kennedy (1990) propose basically similar models that are claimed to be valid throughout the cross-section. These linear models only give good results for very mildly curved bends, but overestimate the strength of the centreregion cell for moderately to strongly curved bends, as illustrated by the experimental data of de Vriend (1981a), Booij & Tukker (1996), Blanckaert (2001) and Blanckaert & de Vriend (2004).…”

Section: Centre-region Cellmentioning

confidence: 99%

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Secondary flow in sharp open-channel bends

2004

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Secondary currents are a characteristic feature of flow in open-channel bends. Besides the classical helical motion (centre-region cell), a weaker and smaller counter-rotating circulation cell (outer-bank cell) is often observed near the outer bank, which is believed to play an important role in bank erosion processes. The mechanisms underlying the circulation cells, especially the outer-bank cell, are still poorly understood, and their numerical simulation still poses problems, not least due to lack of detailed experimental data. The research reported herein provides detailed experimental data on both circulation cells in an open-channel bend such as found in nature. Furthermore, the underlying dynamics are investigated by simultaneously analysing the vorticity equation and the kinetic energy transfer between the mean flow and the turbulence. This shows that turbulence plays a minor role in the generation of the centre-region cell, which is mainly due to the centrifugal force. By accounting for the feedback between the downstream velocity profile and the centre-region cell, a strongly simplified vorticity balance is shown to yield accurate predictions of the velocities in the centre region. For strong curvatures, however, a fully threedimensional flow description is required. Due to the non-monotonic velocity profiles, the centrifugal force favours the outer-bank cell. Moreover, terms related to the anisotropy of the cross-stream turbulence, induced by boundary proximity, are of the same order of magnitude and mainly enhance the outer-bank cell. Both mechanisms strengthen each other. The occurrence of the outer-bank cell is shown to be not just due to flow instability, like in the case of curved laminar flow, but also to kinetic energy input from turbulence.

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Section: Interpretation and Modelling Implicationsmentioning

confidence: 71%

Section: Curved Turbulent Flowmentioning

confidence: 92%

Section: Centre-region Cellmentioning

confidence: 99%

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Secondary flow in sharp open-channel bends

2004

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“…They studied the, by now well known, centre-region cell and discussed the influence of secondary motion on the stream-wise velocity distribution and on the sediment transport. Most studies concentrated on this primary cell far from the banks [4][5][6][7][8]. The centre-region cell occurs due to the imbalance between the driving centrifugal force and the transverse pressure gradient [9].…”

Section: Introductionmentioning

confidence: 99%

Influence of the secondary motions on pollutant mixing in a meandering open channel flow

et al. 2017

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This paper presents large eddy simulation of turbulent flow in a meandering open channel with smooth wall and rectangular cross-section. The Reynolds number based on the channel height is 40,000 and the aspect ratio of the cross-section is 4.48. The depth-averaged mean stream-wise velocity agree well to experimental measurements. In this specific case, two interacting cells are formed that swap from one bend to the other. Transport and mixing of a pollutant is analysed using three different positions of release, e.g. on the inner bank, on the outer bank and on the centre of the cross section. The obtained depth-average mean concentration profiles are reasonably consistent with available experimental data. The role of the secondary motions in the mixing processes is the main focus of the discussion. It is found that the mixing when the scalar is released on the centre of the cross-section is stronger and faster than the mixing of the scalar released on the sides. When the position of release is close to a bank side, the mixing is weaker and a clear concentration of scalar close to the corresponding side-wall can be observed in both cases. Acknowledgements: The simulation was carried out using the supercomputing facilities of the Steinbuch Centre for Computing (SCC) of the Karlsruhe Institute of Technology. The authors would like to thank Clemens Chan-Braun for his valuable and constructive suggestions during the development of this research. MGV acknowledges the financial support of the Spanish Ministry of Education through the program Jose Castillejo.

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“…They studied the, by now well known, centre-region cell and discussed the influence of secondary motion on the stream-wise velocity distribution and on the sediment transport. Most studies concentrated on this primary cell far from the banks (Booij and Tukker, 1996;Muto, 1997;Shiono and Muto, 1998;Tominaga et al, 1999;Booij, 2003). The centre-region cell occurs due to the imbalance between the driving centrifugal force and the transverse pressure gradient (Jia et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Procesos de Mezcla en Flujos Turbulentos con Técnicas de la Mecánica de Fluidos Computacional (CFD)

Esteve¹,

Ignácio²

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3-Dimensional Laser-Doppler Measurements in a Curved Flume

Cited by 8 publications

References 4 publications

Secondary flow in sharp open-channel bends

Secondary flow in sharp open-channel bends

Influence of the secondary motions on pollutant mixing in a meandering open channel flow

Procesos de Mezcla en Flujos Turbulentos con Técnicas de la Mecánica de Fluidos Computacional (CFD)

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