Effect of T-shaped spur dike length on mean flow characteristics along a 180-degree sharp bend

Akbari, Maryam; Vaghefi, Mohammad; Chiew, Yee‐Meng

doi:10.2478/johh-2020-0045

Cited by 24 publications

(4 citation statements)

References 36 publications

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“…In this study, the measured velocities fell within a range of 0 to 1 m/s, which enjoyed an acceptable accuracy considering the stated correlation coefficients. A frequency of 25 Hz and duration of 60 s were used in these experiments, and at sensitive points, the duration was set to 120 s (Akbari et al 2021). The device can record up to 1,500 data of flow velocity per minute in three directions.…”

Section: Methodsmentioning

confidence: 99%

The effect of collar width ratio on the flow pattern around an oblong pier in a bend

2021

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In this paper, the effect of collar width ratio on the flow pattern around an oblong pier in a 180-degree channel bend was experimentally studied. This channel has a rectangular cross section. It is 1 m in width and 0.7 m in height. The upstream and downstream paths are respectively 6.5 and 5 m long. The ratio of the bend's central curvature radius to the channel width is 2; hence, it qualifies as a sharp bend. Experiments were carried out under clear water approach flow conditions. The results showed that the presence of collars around an oblong pier creates vortices in the opposite direction of the longitudinal flow, causes the distortion and disturbance of the streamlines toward the pier downstream, and decreases downflow strength in front of the pier nose. Furthermore, doubling the collar width results in 0.68 and 0.93 times the vorticity and the power of the secondary flow on the pier upstream, respectively. It also reduced the maximum values of the Reynolds stresses perpendicular to the y-plane in x direction and perpendicular to the z-plane in y direction by respectively 45 and 60%, and increased the Reynolds stress perpendicular to the z-plane in x direction by 25%.

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Section: Methodsmentioning

confidence: 99%

The effect of collar width ratio on the flow pattern around an oblong pier in a bend

2021

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“…The analysis is made under clear water conditions; for if a non-rigid bed is assumed, the maximum scour depth occurs under such conditions (Akbari et al, 2021).…”

Section: Numerical Modelmentioning

confidence: 99%

Flow Field in a Sloped Channel with Damaged and Undamaged Piers: Numerical and Experimental Studies

Oveici

Tayari

Jalalkamali

2021

KSCE Journal of Civil Engineering

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This paper analyzed the flow pattern around damaged and undamaged bridge piers in a channel with a mild slope. The experiments were carried out on a straight channel with a length of 12 meters and a slope of 0.008. Acoustic Doppler velocimeter (ADV) was employed to collect three-dimensional flow velocity data, and the results were analyzed and compared with particle image velocimetry (PIV) data. Sediment Simulation in Intakes with Multiblock option (SSIIM) was incorporated for the numerical simulation of the flow in this study. Generally, the results obtained from the comparisons referred to the appropriate agreement between the numerical and the experimental data. The results showed that an undular hydraulic jump occurred at a distance of two meters from the channel entrance in every case; the maximum bed shear stress in the sloped channel was 12 times that in a horizontal channel for installing two damaged and undamaged piers. With this position of the piers in the sloped channel, the upstream water level underwent a 72.5% reduction compared to similar conditions in a horizontal channel, while the amount of this water level decrease was equal to 8.3% compared to the other cases in a sloped channel. In addition, with the presence of both piers, the maximum Froude number was 5.7 times that in a horizontal channel. Open channel flowBridge pier Hydraulic jump Bed shear stress Acoustic Doppler velocimeter CORRESPONDENCE Omid Tayari

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“…The bed shear stress estimated by TKE and the scour process has a direct relation. Maryam 5 compared variations of the mean flow pattern in a 180° bend with a variety of lengths of T-shaped spur dike. The results showed that when the spur dike was placed at the bend apex, the flow strength near that range increased by approximately 2.5 times.…”

Section: Introductionmentioning

confidence: 99%

Characteristics and mechanism of local scour reduction around spur dike using the collar in clear water

Qi,

Wang,

Zou

et al. 2024

Sci Rep

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To reduce the local scour around the spur dike, the U-shaped collar is proposed in this study. The influence of the collar's length, width, and porosity on the local scour reduction in clear water is studied by model tests and numerical simulations. Experimental studies show that the collar has a significant effect on reducing the local scour. The location of the maximum scour depth of the spur dike moves downstream. The width of the collar has the greatest impact on the reduction effect among the three selected factors, followed by the porosity and the length. Local scour reduction efficiency of the collar can reach 56.9%. Based on the regression analysis of the range and variety, a formula for predicting the reduction effect around the spur dike is put forward, and the deviation between the values by formula and that in experiments are within ± 4%. The characteristics of the flow field around the spur dike under constant conditions with a collar are studied via numerical simulation. The numerical simulation results show that compared to the case without collar, the flow velocities around the spur dike in cases with permeable collar and solid collar reduced by 45% and 25%, respectively, and the shear stresses reduced by 20% and 28.6%, respectively. The results of this study can provide a reference for local scour reduction using the solid collar or collar made of permeable materials such as gabions.

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Effect of T-shaped spur dike length on mean flow characteristics along a 180-degree sharp bend

Cited by 24 publications

References 36 publications

The effect of collar width ratio on the flow pattern around an oblong pier in a bend

The effect of collar width ratio on the flow pattern around an oblong pier in a bend

Flow Field in a Sloped Channel with Damaged and Undamaged Piers: Numerical and Experimental Studies

Characteristics and mechanism of local scour reduction around spur dike using the collar in clear water

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