Transverse mixing of pollutants in streams: a review

Sharma, Himanshu; AhmadZ.,

doi:10.1139/cjce-2013-0561

Cited by 16 publications

(7 citation statements)

References 32 publications

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“…Lateral mixing in rivers, including confluences, is related to terms in Equation 1 that include V and v ′, which govern lateral fluxes of tracer (Rutherford, 1994). Lateral advective fluxes of tracer per unit area correspond to VC , whereas lateral transport per unit area by turbulent diffusion equals

\overset{v^{'} c^{'}}{true}

(Sharma & Ahmad, 2014). Of particular interest is variation in VC over depth ( ∂VC / ∂z ), which produces lateral dispersion, stretching, and distortion of a tracer cloud by differential rates of advection.…”

Section: Theoretical Background: Lateral Mixing In Rivers and At Confmentioning

confidence: 99%

Advective Lateral Transport of Streamwise Momentum Governs Mixing at Small River Confluences

Lewis

Rhoads

Sukhodolov

et al. 2020

Water Resources Research

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Confluences are important sites for mixing within river networks. Past work has shown that mixing within confluences is highly variable; in some cases flows mix rapidly and in other cases flows remain unmixed far downstream of the confluence. The fluvial processes that govern mixing within confluences remain poorly understood. This study relates patterns and amounts of mixing to three-dimensional flow structure at three small confluences. It focuses on lateral fluxes of streamwise momentum, which theoretical considerations suggest should influence lateral mixing. Patterns and amounts of mixing differ at the three sites. Considerable mixing occurs at an asymmetrical confluence with strong helical motion within flow from the lateral tributary, which produces substantial differences in advective lateral transport of streamwise momentum over depth. Minor mixing occurs at a comparatively symmetrical confluence where incoming flows have relatively equal momentum fluxes; however, helical motion within one of the flows locally increases mixing. At a symmetrical confluence where one incoming flow has much greater momentum flux than the other, mixing occurs largely through progressive lateral shifting of the mixing interface toward the minor tributary because of the strong lateral flux of streamwise momentum by the dominant tributary. At all three confluences, lateral turbulent transport of streamwise momentum is an order of magnitude less than advective lateral transport of streamwise momentum. The study indicates that generalization of mixing at confluences remains challenging but that advective lateral fluxes of streamwise momentum related to secondary currents (helical motion) or primary flow (cross currents) greatly enhance mixing at confluences.

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\overset{v^{'} c^{'}}{true}

Section: Theoretical Background: Lateral Mixing In Rivers and At Confmentioning

confidence: 99%

Advective Lateral Transport of Streamwise Momentum Governs Mixing at Small River Confluences

Lewis

Rhoads

Sukhodolov

et al. 2020

Water Resources Research

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show abstract

“…Despite the differences, the authors agree that the mixing process and consequently the effective mixing in meandering channels is very different to that in straight channels. Other study conducted by [31] reviewed the different processes in pollutant mixing in river flows as well as the factors affecting the transverse mixing.…”

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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“…Sharma [6] has assessed one weakened street of by Benkelman Beam Deflection method. In view of asphalt condition, it was prescribed to give overlay thickness on existing street.…”

Section: Literature Reviewmentioning

confidence: 99%

A Review Study on the Performance of Flexible Pavements

Jain¹,

Pandey

Saxena³

2023

Macromolecular Symposia

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Pavements are significant resources of expressway infrastructure. The nation has seen colossal expansion in the vehicle population and expanded hub stacking design during the last decade, leaving its street network overemphasized and prompting untimely disappointment. The kind of weakening present in the asphalt ought to be considered for deciding if it has a useful or underlying inadequacy, so that suitable overlay type and configuration can be created. The structural properties of asphalt are redirection and it is completed by Benkelman Beam & deflectometer test. The evaluation of street conditions is needed to distinguish the explanations behind disintegration before any restoration work is completed. The fundamental boundaries including in the appraisal of street conditions are avoidance and unpleasantness estimation which decided utilizing different test, for example, FWD, Benkelman shaft test, profilometer, and slide obstruction test. This appraisal additionally helps in focusing on the upkeep works as indicated by the necessity. A few procedures are utilized to evaluate the road conditions and contrast and standard standards. In this concentrate on a stretch of road is break down for similar where techniques utilized are visual strategy, Benkelman beam test and slide opposition test. The structural and useful assessment are dissected and created by different specialists. The paper presents an itemized audit of different asphalt exhibitions on primary and utilitarian assessment of adaptable asphalt to inspect the job of components identified with asphalt materials, surface deflection, ecological conditions, sort of traffic and volume of traffic, and to distinguish the constraints and holes in the current information on such examinations.

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Transverse mixing of pollutants in streams: a review

Cited by 16 publications

References 32 publications

Advective Lateral Transport of Streamwise Momentum Governs Mixing at Small River Confluences

Advective Lateral Transport of Streamwise Momentum Governs Mixing at Small River Confluences

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

A Review Study on the Performance of Flexible Pavements

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