Numerical Simulation of Flow and Scour in a Laboratory Junction

Ahadiyan, Javad; Adeli, Atefeh; Bahmanpouri, Farhad; Gualtieri, Carlo

doi:10.3390/geosciences8050162

Cited by 28 publications

(2 citation statements)

References 30 publications

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“…These three categories can be: 1) numerical modeling and/or fieldwork, 2) physical modeling of sediment pattern, and 3) physical modeling of flow pattern. Among the studies that evaluate the flow and sediment patterns of river confluence by numerical modeling and/or fieldwork, one can mention Bradbrook et al (2001), Boyer et al (2006), Shakibainia et al (2010), Constantinescu et al (2011Constantinescu et al ( , 2012, Bahmanpouri et al (2017), Ahadiyan et al (2018), Gualtieri et al (2018), Gualtieri et al (2019), Balouchi et al (2021), Bahmanpouri et al (2022). Besides some studies investigated the effect of geometric and hydraulic conditions on sedimentation pattern such as Ghobadian and Shafai Bejestan (2007), Borghei and Jabbari Sahebari (2010), Balouchi and Shafai Bejestan (2012), Nazari Giglou et al (2016), Amini et al (2017), Wuppukondur and Chandra (2017).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of flow pattern over a fully developed bed at a 60° river confluence in large floods

et al. 2022

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River confluences have a complex flow and sedimentation pattern that have vital influences on the hydraulic and bed morphology of river reach and the surrounding area. Confluences can be observed in waterways with various situations such as live bed conditions. This condition is a hydro-morphological situation with a high densimetric Froude number, i.e., bed load transport is supplied from upstream. According to the literature review, most of the experimental studies investigate the flow pattern on the flatbed and not on the developed riverbed, or/and in the low densimetric Froude number, or/and without supplying the sediment from upstream. Therefore, in the present study for the quantification of the flow pattern under these conditions, each developed bed was fixed with the cement blanket method in the laboratory. Then, the 3D velocity was measured at specific points at the confluence. The current study was designed to understand the flow pattern corresponding to the river bed behavior in the case of large floods. It is expected that the morphological features downstream of the confluence have a different pattern than the ones in the condition described in other literature. Thus, this paper describes briefly what are the different bed features and investigates the corresponding flow pattern. The results of the flow pattern on the developed bed show that all zones at the river confluence can be observed except the point bar due to the approximate equality of the mean longitudinal velocity of the separation zone and the main channel upstream of the confluence. Moreover, results show that by increasing the bedload ratio (sediment discharge to water discharge of the main channel of upstream of the confluence) from 0 to 3 × 10−4, flow deflection to the outer bank of the channel decreased down to 45%, the stagnation equivalent area decreased down to 2.5 times, and bed shear stress decreased down to 40%. Hence, the momentum of lateral flow decreased with increasing bedload. Besides, the recovery zone occurred at a longer distance after the confluence compared to the case without bedload. Hence, the location of the maximum velocity zone, vortices, and secondary flows changed downstream of the confluence, by changing the bed load value.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation of flow pattern over a fully developed bed at a 60° river confluence in large floods

et al. 2022

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“…하천 합류부에서는 조건과 환경에 따 라 지류의 퇴적물이 상대적으로 유속이 느린 본류에 진 입하게 되며 발생하는 퇴적 작용으로 삼각주가 형성되기 도 한다. 합류 지역에 생긴 삼각주 지형은, 본류의 형태 와 수리학적 특성에 영향을 주기도 하고 본류의 영향을 받아 형태 변화가 나타나기도 한다 (Savi et al, 2020 Kim, & Ko, 2006;Choi, Mo, & Lee, 2015;Schindfessel, Creëlle, & De Mulder, 2015;Kim & Jang, 2016;C.-L. Jang, 2017;E.-K. Jang & Ji, 2017;Park, Kim, & Baek, 2018;Ahadiyan, Adeli, Bahmanpouri, & Gualtieri, 2018). Eq.…”

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Dynamic Equilibrium Position Prediction Model for the Confluence Area of Nakdong River

Kim,

Shin,

Nahm

et al. 2023

Econ. Environ. Geol.

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A delta is a depositional landform that is formed when sediment transported by a river is deposited in a relatively low-energy environment, such as a lake, sea, or a main channel. Among these, a delta formed at the confluence of rivers has a great importance in river management and research because it has a significant impact on the hydraulic and sedimentological characteristics of the river. Recently, the equilibrium state of the confluence area has been disrupted by large-scale dredging and construction of levees in the Nakdong River. However, due to the natural recovery of the river, the confluence area is returning to its pre-dredging natural state through ongoing sedimentation. The time-series data show that the confluence delta has been steadily growing since the dredging, but once it reaches a certain size, it repeats growth and retreat, and the overall size does not change significantly. In this study, we developed a model to explain the sedimentation-erosion processes in the confluence area based on the assumption that the confluence delta reaches a dynamic equilibrium. The model is based on two fundamental principles: sedimentation due to supply from the tributary and erosion due to the main channel. The erosion coefficient that represents the Nakdong River confluence areas, was obtained using data from the tributaries of the Nakdong River. Sensitivity analyses were conducted using the developed model to understand how the confluence delta responds to changes in the sediment and water discharges of the tributary and the main channel, respectively. We then used annual average discharge of the Nakdong River's tributaries to predict the dynamic equilibrium positions of the confluence deltas. Finally, we conducted a simulation experiment on the development of the Gamcheon-Nakdong River delta using recorded daily discharge. The results showed that even though it is a simple model, it accurately predicted the dynamic equilibrium positions of the confluence deltas in the Nakdong River, including the areas where the delta had not formed, and those where the delta had already formed and predicted the trend of the response of the Gamcheon-Nakdong River delta. However, the actual retreat in the Gamcheon-Nakdong River delta was not captured fully due to errors and limitations in the simplification process. The insights through this study provide basic information on the sediment supply of the Nakdong River through the confluence areas, which can be implemented as a basic model for river maintenance and management.

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Investigation on flow field near confluence of two rigid channels at zero-degree

Ansari,

Ahmad

2024

Environ Fluid Mech

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Numerical Simulation of Flow and Scour in a Laboratory Junction

Cited by 28 publications

References 30 publications

Experimental investigation of flow pattern over a fully developed bed at a 60° river confluence in large floods

Experimental investigation of flow pattern over a fully developed bed at a 60° river confluence in large floods

Dynamic Equilibrium Position Prediction Model for the Confluence Area of Nakdong River

Investigation on flow field near confluence of two rigid channels at zero-degree

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