Experimental analysis of sediment incipient motion in rigid boundary open channels

Safari, Mir Jafar Sadegh; Aksoy, Hafzullah; Ünal, N. Erdem; Mohammadi, Mirali

doi:10.1007/s10652-017-9550-z

Cited by 34 publications

(13 citation statements)

References 23 publications

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“…Figure 9 shows the difference between Shields curve plotted from Chien and Wan (1999) and the plots obtained for smooth bed from Novak and Nalluri (1975); Safari et al (2017) and in the present study. From the study carried out by Novak and Nalluri (1975) in a rectangular channel taking singular particles from 0.6 to 50 mm, Nsh can be expressed as:…”

Section: Critical Condition and The Regime Of Particle Motionmentioning

confidence: 55%

“…The primary governing factors for the sediment transport are the fluid, flow and sediment characteristics (Garde and Albertson 1959;Garde and Ranga Raju 2015). However, the threshold condition for particle motion on a smooth bed is inferior to that for alluvial bed and the Shields method overestimates the critical condition for smooth bed (Bridge and Dominic 1984;Nalluri 1975, 1984;Ramesh et al 2011;Safari et al 2017).…”

Section: Manuscript_r1mentioning

confidence: 93%

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Sediment Movement over Type A Piano Key Weirs

Kumar

Kadia

Ahmad

2021

J. Irrig. Drain Eng.

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This investigation deals with the mechanics of movement of singular quartz gravel and coarse sand river bed particles in upstream and over inlet key of three type-A Piano key weir (PKW) models, which were recorded with a high-speed camera. Acoustic-Doppler-Velocimeter was used to obtain the upstream bed shear stress. The sediment threshold and regime over the upstream bed were compared with the previous investigations and found to be within the ranges. Generally, a sediment particle decelerates as it approaches the inlet key, but accelerates over it due to flow contraction and an increase in shear stress.Rolling and saltation regimes were observed over the key. The maximum particle velocity at the key end was higher in case of 1-cycle model than 2-cycles than 3-cycles. CFD simulation shows a rapid increase in shear stress at the key end. For the used models, PKW required 17%-43% of additional shear stress on the upstream bed to pass sediment over the key. This study is useful for the in-channel application of PKW and sediment flushing over it.

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Section: Critical Condition and The Regime Of Particle Motionmentioning

confidence: 55%

Section: Manuscript_r1mentioning

confidence: 93%

Sediment Movement over Type A Piano Key Weirs

Kumar

Kadia

Ahmad

2021

J. Irrig. Drain Eng.

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“…Sediment particles in the rigid boundary channels are gathered from surrounding area and depend on the catchment characteristics. Consequently, a direct application of loose boundary channels sediment transport models in rigid boundary channels is not recommended [43,44]. Motivated by the channel design considerations, sediment transport studies typically focus on three basic sediment movement conditions of incipient deposition, incipient motion and nondeposition.…”

Section: Sediment Transport In Rigid Boundary Open Channelsmentioning

confidence: 99%

Kernel ridge regression model for sediment transport in open channel flow

Safari

Arashloo

2021

Neural Comput & Applic

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Sediment transport modeling is of primary importance for the determination of channel design velocity in lined channels. This study proposes to model sediment transport in open channel flow using kernel ridge regression (KRR), a nonlinear regression technique formulated in the reproducing kernel Hilbert space. While the naı ¨ve kernel regression approach provides high flexibility for modeling purposes, the regularized variant is equipped with an additional mechanism for better generalization capability. In order to better tailor the KRR approach to the sediment transport modeling problem, unlike the conventional KRR approach, in this study the kernel parameter is directly learned from the data via a new gradient descentbased learning mechanism. Moreover, for model construction, a procedure based on Cholesky decomposition and forwardback substitution is applied to improve the computational complexity of the approach. Evaluation of the recommended technique is performed utilizing a large number of laboratory experimental data where the examination of the proposed approach in terms of three statistical performance indices for sediment transport modeling indicates a better performance for the developed model in particle Froude number computation, outperforming the conventional models as well as some other machine learning techniques.

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“…Having addressed the flow velocity direction in meandering channels, Liu et al [15] developed a model for calculating the mean 2D flow velocity. Safari et al [16] carried out an experimental investigation of the incipient motion in a straight channel with different cross sections, including trapezoidal, rectangular, circular, U-shaped, and V-shaped ones. Their results indicated that rectangular and V-shaped cross sections, respectively, require the minimum and the maximum velocity and shear stress to reach sediment incipient motion.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mean Velocity-to-Critical Velocity Ratios on Bed Topography and Incipient Motion in a Meandering Channel: Experimental Investigation

Moghaddassi

Musavi-Jahromi

Vaghefi

et al. 2021

Water

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As 180-degree meanders are observed in abundance in nature, a meandering channel with two consecutive 180-degree bends was designed and constructed to investigate bed topography variations. These two 180-degree mild bends are located between two upstream and downstream straight paths. In this study, different mean velocity-to-critical velocity ratios have been tested at the upstream straight path to determine the meander’s incipient motion. To this end, bed topography variations along the meander and the downstream straight path were addressed for different mean velocity-to-critical velocity ratios. In addition, the upstream bend’s effect on the downstream bend was investigated. Results indicated that the maximum scour depth at the downstream bend increased as a result of changing the mean velocity-to-critical velocity ratio from 0.8 to 0.84, 0.86, 0.89, 0.92, 0.95, and 0.98 by, respectively, 1.5, 2.5, 5, 10, 12, and 26 times. Moreover, increasing the ratio increased the maximum sedimentary height by 3, 10, 23, 48, 49, and 56 times. The upstream bend’s incipient motion was observed for the mean velocity-to-critical velocity ratio of 0.89, while the downstream bend’s incipient motion occurred for the ratio of 0.78.

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Experimental analysis of sediment incipient motion in rigid boundary open channels

Cited by 34 publications

References 23 publications

Sediment Movement over Type A Piano Key Weirs

Sediment Movement over Type A Piano Key Weirs

Kernel ridge regression model for sediment transport in open channel flow

Effect of Mean Velocity-to-Critical Velocity Ratios on Bed Topography and Incipient Motion in a Meandering Channel: Experimental Investigation

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