An Investigation of Flow Behaviour at the Junction of Rectangular Channels.

Webber, N.B.; Greated, Clive

doi:10.1680/iicep.1966.8925

Cited by 110 publications

(53 citation statements)

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“…This acceleration is strongest at the wall of the tributary adjacent to the separation zone (right wall), and thus there the highest flow velocities are observed (Gurram & Karki 1997). A similar conclusion is found with the help of conformal mapping theory (Webber & Greated 1966). Since head losses in the tributary are small, the local acceleration along the wall is inseparable from local decreases in the water depth (Gurram & Karki 1997, Ramamurthy et al 1988.…”

Section: Introductionsupporting

confidence: 63%

Experimental investigation of the flow evolution in the tributary of a 90° open channel confluence

Creëlle¹,

Schindfessel²,

Ramos³

et al. 2016

River Flow 2016

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Section: Introductionsupporting

confidence: 63%

Experimental investigation of the flow evolution in the tributary of a 90° open channel confluence

Creëlle¹,

Schindfessel²,

Ramos³

et al. 2016

River Flow 2016

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“…Next to the separation zone, the merging flows passing through a narrowed cross-section are contracted, leading to increased velocities. From the very beginning of laboratory research on confluences, starting with Taylor [2], the ratio of incoming discharges has been recognized as a key parameter [1][2][3][4][5][6][7][8][9][10][11][12][13]. However, laboratory research was mainly performed with discharge ratios in the range of 0.1 ≲ q ≲ 0.9, at least for the case of asymmetrical confluences with a fixed concordant bed and subcritical flow throughout [12]; the type of confluence that will be further considered in this paper.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Webber & Greated [3] observed a decreasing accuracy of their theoretical model at lower q. Gurram et al [6] were the first to provide a qualitative view on the case where q = 0 (i.e., all flow coming from the tributary) by means of photographs. They noted the significant impact of the tributary flow on the opposing wall, and alluded to flow in a mitre bend.…”

Section: Introductionmentioning

confidence: 99%

Flow Patterns in an Open Channel Confluence with Increasingly Dominant Tributary Inflow

Schindfessel

Creëlle

Mulder

2015

Water

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Despite the ratio of incoming discharges being recognized as a key parameter in open-channel confluence hydrodynamics, little is known about the flow patterns when the tributary provides more than 90% of the total discharge. This paper offers a systematic study of flow features when the tributary becomes increasingly dominant in a 90° confluence with a fixed concordant bed. Large-eddy simulations are used to investigate the three-dimensional complex flow patterns for three different discharge ratios. It is found that the tributary flow impinges on the opposing bank when the tributary flow becomes sufficiently dominant, causing a recirculating eddy in the upstream channel of the confluence, which induces significant changes in the incoming velocity distribution. Moreover, it results in stronger helicoidal cells in the downstream channel, along with zones of upwelling flow. In turn, the changed flow patterns also influence the mixing layer and the flow recovery. Finally, intermittent events of stronger upwelling flow are discerned. Improved understanding of flow patterns at confluences where the tributary is dominant is applicable to both engineering and earth sciences.

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“…Afterwards, Webber and Greated (1966) conducted laboratory experiments to describe the bulk flow variables at the junction of rectangular open-channels. Best (1987) identified and described six main distinctive zones/features in river confluences: flow deflection, flow stagnation, flow separation, maximum velocity, shear layers and flow recovery (see Fig.…”

mentioning

confidence: 99%

Three dimensional flow field at confluent fixed-bed open channels

Birjukova¹,

Ludeña²,

Alegria³

et al. 2014

River Flow 2014

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River confluences are known for their marked 3D patterns and, due to the complexity of local flow features and bed morphology, they require particular consideration. Although there are studies on the flow structure in junctions of two streams, amore detailed description of the flow patterns is still required. The objective of this work is to contribute to such description at river confluence for concordant bed, where both main and tributary channel beds have the same elevation. For that purpose, a set of experiments with fixed bed under quasi-uniform approach flow conditions was carried out. The experimental facility included a 12 m long and 1 m wide main channel, and a 4.5 m long and 0.15 m wide tributary channel. The confluence angle was 70° so as to represent common natural conditions and the discharge ratio between discharges in the tributary and in the main channel was kept constant. An Acoustic Doppler Velocimeter (ADV) with a side-looking configuration was used to measure the three components of flow velocity on a dense grid of measuring points, providing the accurate characterization of the mean flow and second-order velocity moments. The acquired data set constitutes the most refined characterization of river confluence flow structures known to date, due to the adopted temporal and spatial discretization, and may serve for the validation of 3D numerical models of complex confluent flows. Flow dynamics zones typical of confluent beds are present in the studied case. The separation zone limits the effective lateral flow cross-section, and, hence, results in the added acceleration of the mainstream flow near the downstream junction corner. The upward orientated vertical velocities of high magnitude were observed all along the separation zone.

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An Investigation of Flow Behaviour at the Junction of Rectangular Channels.

Cited by 110 publications

References 0 publications

Experimental investigation of the flow evolution in the tributary of a 90° open channel confluence

Experimental investigation of the flow evolution in the tributary of a 90° open channel confluence

Flow Patterns in an Open Channel Confluence with Increasingly Dominant Tributary Inflow

Three dimensional flow field at confluent fixed-bed open channels

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