Erosive and hydrodynamic processes downstream of low-head control structures

Pagliara, Stefano; Palermo, Michele; Kurdistani, Sahameddin Mahmoudi; Hassanabadi, Leila

doi:10.1080/23249676.2014.1001880

Cited by 18 publications

(4 citation statements)

References 40 publications

(55 reference statements)

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“…Likewise, Guan et al [4] and Wang et al [5,6] studied flows past vertical and sloped submerged weirs. Pagliara and Palermo [7] and Pagliara et al [8] analyzed similarities and differences in the flow behavior, and highlighted the main parameters affecting the scour process downstream of stepped gabion weirs, rock, grade-control structures, block ramps, and cross-vane weirs. They determined that the most important parameters were the tailwater depth and the densimetric Froude number.…”

Section: Introductionmentioning

confidence: 99%

The Phenomenological Theory of Turbulence and the Scour Evolution Downstream of Grade-Control Structures under Steady Discharges

Nardi

Palermo

Bombardelli

et al. 2021

Water

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A more complete understanding of scour mechanisms for flows downstream of grade-control structures, including their temporal evolution, has the potential to lead to improved predicting tools for design. To date, design equations have been mostly derived empirically, i.e., by parametric modelling (at generally-small scales) corresponding to specific structure configurations, and for limited ranges of hydraulic conditions. Although these approaches allowed different authors to propose many empirical and/or semi-empirical equations, they lack generality and may lead to incorrect estimations when applied outside their ranges of validity. First-principles-based methods with solid calibration and validation procedures can overcome these issues. Following recent theoretical advancements presented elsewhere by the last three authors, in this work we analyze and test the predictive capability of a scour evolution model based on the phenomenological theory of turbulence (PTT) by using a large dataset pertaining to different grade-control structures. Although the PTT model was developed (and validated) for scour evolution caused by oblique and vertical plunging jets, we show that its basic assumptions are still valid for the addressed low-head structures, encompassing rock structures, stepped gabion weirs, rock and bed sills, and others. Furthermore, we also provide interesting insights on scour evolution by contrasting the predicting capability of our model against experimental data by different authors for specific structures. Results of the comparison conclusively show that the PTT model has a general validity and represents a trustable tool to estimate scour evolution regardless of the structure configuration and hydraulic conditions.

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Section: Introductionmentioning

confidence: 99%

The Phenomenological Theory of Turbulence and the Scour Evolution Downstream of Grade-Control Structures under Steady Discharges

Nardi

Palermo

Bombardelli

et al. 2021

Water

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“…To this end, we must know well something more about the effluent flow characteristics and sea conditions, than initial and boundary conditions, in advance in order to obtain a solution. Self-similarity which means reproducing itself on different time and space scales is the right solution to reduce a problem in the mathematical physics of a phenomenon that generally leads to a power-law relationship confirmed in previous studies by several authors [38][39][40][41][42].…”

Section: Dimensional Analysismentioning

confidence: 67%

Diffusion of a Surface Marine Sewage Effluent

Sahameddin Mahmoudi Kurdistani,

Gianluca Cosimo Perrone

2023

CFDL

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Any scalar concentration discharging to the sea through a freshwater release is a thermodynamic two-phase flow including different densities and different temperatures. Because of Reynolds similarity, physical models are not feasible to use and numerical models such as CFD-RANS are the solutions. A series of numerical experiments have been conducted to derive an empirical formula that determines the length of the 95% scalar concentration reduction, useful for primary and emergency engineering-environmental decisions. Results show that the scalar concentration intrusion length is a function of seawater density-temperature, freshwater density-temperature, sea current Froude number, effluent jet Froude number, and the scalar concentration in which among those, the sea current Froude number has the most effective role in which as an example of the lowest and highest tested sea current velocities, an effluent discharge of 0.052 m3/s with a concentration of 1 Kg/m3 and effluent jet velocity 0.245 m/s in 3.2 meters from the effluent source reaches to the 95% scalar concentration reduction when there is a high-velocity sea current (0.5 m/s) while in the presence of a low-velocity sea current (0.05 m/s), the same effluent discharge with the same scalar concentration and the same effluent jet velocity, the length of the 95% scalar concentration reduction increase to 42.8 meters from the effluent source.

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“…Many studies have investigated the local scour at weir‐like structures and proposed empirical scour predictors for unsubmerged or partially submerged weirs (Ben Meftah & Mossa, 2006; Bormann & Julien, 1991; D'Agostino & Ferro, 2004; Gaudio et al, 2000; Lenzi et al, 2002, 2003a, 2003b; Marion et al, 2004, 2006; Pagliara & Kurdistani, 2013; Pagliara et al, 2015; Palermo & Pagliara, 2018; Tregnaghi et al, 2007, 2009, 2010, 2011; Scurlock et al, 2012), as well as fully submerged weirs (Guan et al, 2015, 2016; Wang, Melville, & Guan, 2018, Wang, Melville, Guan, & Whittaker, 2018, 2019). However, as the upstream bridge pier has the potential to change the local flow pattern and scour process at the submerged weir, it is inappropriate to assume that the scour at the submerged weir downstream of a bridge is the same as that of a single submerged weir.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Bridge Piers on Scour at Downstream River Training Structures: Submerged Weir as an Example

Wang

Melville

Shamseldin

et al. 2020

Water Resources Research

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River training structures are conventionally used to improve river stability and ecological conditions and to protect the upstream instream infrastructures from scour and erosion. A submerged weir is a typical river training structure usually built downstream of bridges for grade control. Flow over the weir can cause local scour, destabilizing both the structure and the trained river reach. It is therefore important for safe design to estimate the scour accurately and understand the effects of an upstream bridge pier on local scour at submerged weirs. This study describes experiments on the scour process at a submerged weir with an upstream bridge pier, varying the distance L between the two. In this study, 56 experiments were conducted using uniform coarse sand with a median grain size d 50 = 0.85 mm in a sediment-recirculating flume. For clear-water scour, the experiments showed that the bedform induced by the pier scour process creates a scour-and-fill process upstream of the submerged weir; and the upstream pier can also affect the scour downstream of the submerged weir, through two mechanisms: (i) upstream sediment replenishment and (ii) flow section constriction. The mechanisms (i) and (ii) can reduce and increase the downstream clear-water scour depth at the submerged weir, respectively. For live-bed scour, a pier upstream can reduce and increase the scour depth upstream and downstream of the submerged weir, respectively. Based on the experimental data, the dependence of the scour depth at the submerged weir on L is evaluated.

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Erosive and hydrodynamic processes downstream of low-head control structures

Cited by 18 publications

References 40 publications

The Phenomenological Theory of Turbulence and the Scour Evolution Downstream of Grade-Control Structures under Steady Discharges

The Phenomenological Theory of Turbulence and the Scour Evolution Downstream of Grade-Control Structures under Steady Discharges

Diffusion of a Surface Marine Sewage Effluent

Impacts of Bridge Piers on Scour at Downstream River Training Structures: Submerged Weir as an Example

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