Experimental investigation on flow and scour characteristics around tandem piers in sandy channel with downward seepage

Chavan, Rutuja; Kumar, Bimlesh

doi:10.1007/s11804-017-1426-6

Cited by 15 publications

(5 citation statements)

References 27 publications

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“…Therefore, excavation of a mining pit in the channel leads to greater scour depth and higher volume of sediment extraction at the base of the pier front. The nature of the velocity profiles along the depth for both cases at Location 2 is in agreement with previous studies [17,28]. In the central regions of both piers, mean velocities are higher near the bed up to z/h ~ 0.3, and above this depth, velocities drop significantly for both experimental cases (Figure 4c).…”

Section: Time Averaged Flow Fieldsupporting

confidence: 91%

“…Very low streamwise velocities were observed in this region. Due to this, deposition of sediment occurred along the centerline at the downstream side of P2, which leads to the formation of a dune-like structure [17]. The maximum height of the dune was found to be 22 mm (above the initial bed level) and it was observed at 1200 mm downstream of P1.…”

Section: Morphological Featuresmentioning

confidence: 96%

“…They found that the wake behind the tandem piers is significantly different from a single pier and turbulence intensities are higher near the downstream pier. Chavan and Kumar [17] studied the effect of seepage on the turbulence around the tandem piers in a mobile bed. They observed stronger flow reversal in the horseshoe vortex region in the presence of downward seepage.…”

Section: Introductionmentioning

confidence: 99%

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On the Morphodynamic Alterations around Bridge Piers under the Influence of Instream Mining

Lade

Deshpande

Kumar

et al. 2019

Water

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Sand mining in an active alluvial channel can compromise the streambed stability of the hydraulic structures nearby. This experimental study is aimed at investigating the effects of rectangular mining pit on the morphodynamics around circular tandem piers in a movable bed. A rectangular pit is excavated upstream of two circular piers embedded in the sand-bed in a tandem arrangement. The results are then compared to a case having only the piers without any mining pit. Turbulent stresses and mean velocities in the near-bed region rise significantly at the upstream region of the piers in the presence of a pit. Also, stronger flow reversal and horseshoe vortices have been detected at the base of the pier front. Due to these alterations in the nature of turbulence, erosion of channel beds upstream of the piers, increased scour depths, scour volume, and lateral erosion of the scour hole have been observed. Dynamic evolution of the local scour at various time scales has been studied using a wavelet cross-correlation method. Spatial evolution of local scour is found to be faster when a pit is excavated in the channel. Thus, mining activities near the piers can lead to significant changes in the flow-field, causing excessive scour around piers.

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Section: Time Averaged Flow Fieldsupporting

confidence: 91%

Section: Morphological Featuresmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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On the Morphodynamic Alterations around Bridge Piers under the Influence of Instream Mining

Lade

Deshpande

Kumar

et al. 2019

Water

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“…Wang et al [18] studied the local scouring around three piers in a tandem ent in clear water conditions. Chavan et al [19] studied the flow and scour characteristics andem piers in sandy channels with downward seepage. Beg et al [20] studied the scour Many experimental and numerical studies have investigated flow fields around a bridge pier and pier groups [1][2][3].…”

Section: Arrangements Of Piers Resultsmentioning

confidence: 99%

Numerical Simulation of Velocity Field around Two Columns of Tandem Piers of the Longitudinal Bridge

Zheng

Zhang

2020

Fluids

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This research explores the effects of different spans of two columns of tandem piers on the characteristics of x-velocity near the river bed based on computational fluid dynamics (CFD) simulations. With a span shorter than 27.5D (D is the diameter of piers), the shape and the lateral range of the x-velocity increases with the increase of distance downwards the x-direction. For the area between the tandem piers and the wall, the VRi/VR1 (the ratio of the x-velocity at the i-th row to the x-velocity of the first row in each model) near the wall increases up to 1.26. For the area between the two columns of tandem piers, the profile of VRi/VR1 changes from a “∩-shape” to an “M-shape” in each model. RAVC (average velocity change ratio) of different spans increases gradually and tends to be stable with the increases of the span. The largest RAVC is about −17.66% with a span of 0.52 m. The RMV (the ratio of the maximum x-velocity among piers in each row in different models to the maximum x-velocity of the two piers arranged side by side) of piers in the first row of different models is around 0.95. The RMV becomes 0.82 at the second pier in each model when the span is shorter than 27.5D, and increases to 0.91 if the span is longer than 27.5D. If the span is longer than 27.5D, the RMV of different piers are close to each other from the 2nd pier to the last one.

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“…The distribution of the turbulent quantities, such as the sediment transport, is affected by the interaction between the bridge pier and flow. Chavan et al [9,31] observed that the velocity and Reynolds stresses are negative upstream of the pier and close to bed, and downstream of the pier and close to the free surface, because of reversal flow, which causes a horseshoe vortex at the bed and a wake vortex at the free surface. In this paper, in order to deeply analyze the turbulent quantities and sediment transport around a bridge pier, upstream (U), downstream (D) and laterally against (S1 and S2) the pier, the distributions of the higher order moments (i.e., turbulence intensity and skewness), turbulent kinetic energy budget, and fluxes of turbulent kinetic energy, have been experimentally studied.…”

Section: Turbulence Characteristicsmentioning

confidence: 99%

Turbulent Flow Structures and Scour Hole Characteristics around Circular Bridge Piers over Non-Uniform Sand Bed Channels with Downward Seepage

Chavan¹,

Gualtieri

Kumar

2019

Water

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In alluvial rivers bridge piers often cause local scour, a complex phenomenon as a result of the interaction between turbulent flow and bed material. In this paper, the results of an experimental study on the scour hole characteristics around single vertical pier sets on a non-uniform sand bed, under no seepage, and with downward seepage conditions, are described. In case of downward seepage, turbulent statistics, such as Reynolds stress, higher order moments, TKE-flux, and consequently sediment transport, decrease upstream of the pier, while increasing on both sides of it, where the enhanced erosive capacity of the flow results in an increase in the scour hole width. Moreover, the scour hole length shifts downstream. Empirical equations for the evaluation of scour hole characteristics, such as the length, width, area, and volume, including the downward seepage parameter, are proposed and experimentally tested. Model predictions give reasonably good agreement with the experimental data.

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Experimental investigation on flow and scour characteristics around tandem piers in sandy channel with downward seepage

Cited by 15 publications

References 27 publications

On the Morphodynamic Alterations around Bridge Piers under the Influence of Instream Mining

On the Morphodynamic Alterations around Bridge Piers under the Influence of Instream Mining

Numerical Simulation of Velocity Field around Two Columns of Tandem Piers of the Longitudinal Bridge

Turbulent Flow Structures and Scour Hole Characteristics around Circular Bridge Piers over Non-Uniform Sand Bed Channels with Downward Seepage

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