CFD modeling of scale effects on turbulence flow and scour around bridge piers

Huang, Wenrui; Yang, Qiping; Xiao, Hong Wei

doi:10.1016/j.compfluid.2008.01.029

Cited by 62 publications

(33 citation statements)

References 11 publications

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“…Numerical simulations may serve as a more frequently used alternative for the investigation of phenomena such as turbidity currents or distensible structures, which may not be addressed in physical models without significant scale effects or simulations may even play a role in the quantification of scale effects as shown by Huang et al (2009) for turbulent flows and bridge pier scour. A Direct Numerical Simulation includes the full Navier -Stokes equations and therefore also, for example, the kinematic viscosity responsible for scale effects in a Froude model.…”

Section: Future Research Directionsmentioning

confidence: 99%

Scale effects in physical hydraulic engineering models

Heller

2011

Journal of Hydraulic Research

483

232

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Beside analytical approaches, physical modelling represents probably the oldest design tool in hydraulic engineering. It is thus a pleasure to see this Forum Paper in JHR. The Discussers focus on one aspect of the publication, thereby specifying the information of the Forum Paper. Free surface flows are typically scaled with the Froude similitude keeping identical F = V /(gh) 0.5 both in the model and in the prototype. The air transport in models is affected by scale effects because the internal flow turbulence, represented by the Reynolds number R = Vh/ν, is underestimated, while surface tension, represented by the Weber number W = (ρV 2 h)/σ , is overestimated (Chanson 2009), with V = flow velocity, g = gravity constant, h = flow depth, ρ = water density, σ = water surface tension, and ν = water kinematic viscosity. Because a strict dynamic similitude exists only at a full-scale, the underestimation of the air transport is minimized if limitations in terms of W or R are respected. The Forum Paper overlooks a number of aspects and probably recommends too optimistic limitations. As stated in Table D1, the literature mentions limitations around W 0.5 = 110-170 and R = 1.0-2.5 × 10 5. These values focus on air entrainment at hydraulic jumps, general chute air entrainment and aerated stepped spill-way flows, as well as the air entrainment coefficient β and the streamwise bottom air concentration C b generated by chute aer-ators. Pfister and Hager (2010a, b) identified an underestimation up to one magnitude in terms of C b if W 0.5 < 140 (Fig. D1). There, the abscissa corresponds to the streamwise normalization given by these authors, and the trend lines correspond to the best fit of all C b curves from tests with W 0.5 ≥ 140, i.e. without significant scale effects. As can be noted from Table D1, two criteria are often applied relating to the herein discussed scale effects, i.e. limiting values for W 0.5 and R for a range of air-water flow parameters. This results in an over-determined system, as the two numbers depend on each other, besides F and the Morton number M. The latter characterizes the shape of bubbles or drops moving in a surrounding medium, solely as a function of the fluid properties and the gravity constant (Wood 1991, Chanson 1997). With a negligible inner bubble density, as is typical for air-water flows, the Morton number is with μ = dynamic water viscosity M = gμ 4 σ 3 ρ = W 3 F 2 R 4 (D1) For air-water two-phase flows M = 3.89 × 10 −11. If using the Froude similitude: (1) M = constant, and (2) F is similar in the model and the prototype. Isolating these two numbers results in MF 2 = W 3 R 4 (D2) For a given F, the right-hand side of Eq. (D2) thus has to be identical both in the model and in the prototype flows. The theoretical function MF 2 versus F is shown in Fig. D2(a). The theoretical MF 2 values (curve) are identical with the experimentally derived W 3 /R 4 values (symbols; Pfister and Hager 2010a, 2010b), as expected from Eq. (D2). To visualize the limitations, Fig. D2(b) shows the measured...

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Section: Future Research Directionsmentioning

confidence: 99%

Scale effects in physical hydraulic engineering models

Heller

2011

Journal of Hydraulic Research

483

232

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“…It is also used to systematically study the effect of pier configurations on the flow and scour patterns. The configuration variables mainly include geometric scale (Huang et al 2009), cross section shape (Guemou et al 2013), stream attack angle (Tao et al 2013), and so on.…”

Section: Introductionmentioning

confidence: 99%

Streamlining of Bridge Pier as a Scour Countermeasure: A Feasibility Study

Tao

2015

Ifcee 2015

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Scour around bridge pier is known as one of the most critical causes to bridge failure. Countermeasures suggested by HEC-23 (2009) include riprap, gabions, spurs, guide banks, and so on. The principals of these countermeasures are either mechanically stabilizing the channel bed surface to prevent the development of the scour hole, or reducing the vortex intensity. Streamlining of the piers is a potentially feasible countermeasure to bridge scour by reducing the vortex strength. In this paper, Computational Fluid Dynamics (CFD) models are developed to evaluate the feasibility of streamlining as a countermeasure. Five test cases with different streamlining features are systematically analyzed and compared. It is found that the vertical profile of the pier nose and sidewalls has significant effects on the development of vortex structures around piers. Streamlined pier nose and sidewalls help reduce the downward flow in front of the piers, the vortex extent around the pier and the bed shear stress intensity. If the pier is not aligned with the incoming flow, however, the effectiveness of streamlining as a scour countermeasure may be highly compromised.

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“…However, some limitations existed, such as the 2D model could only simulate vertically averaged currents instead of 3D currents in this study, in particular about the vertical velocity component [28]. Huang et al [29] pointed out that the approximation of the 3D scour phenomenon around the pile structure to a 2D problem may be a contribution to errors between the model predictions and observations. To the authors' knowledge, the research of 3D modeling in this question is still limited so far and yet to be further investigated.…”

Section: Introductionmentioning

confidence: 97%

3D Modeling and Mechanism Analysis of Breaking Wave-Induced Seabed Scour around Monopile

Liu

Zhu

et al. 2020

Mathematical Problems in Engineering

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Breaking wave-induced scour is recognized as one of the major causes of coastal erosion and offshore structure failure, which involves in the full 3D water-air-sand interaction, raising a great challenge for the numerical simulation. To better understand this process, a nonlinear 3D numerical model based on the open-source CFD platform OpenFOAM® was self-developed in this study. The Navier–Stokes equations were used to compute the two-phase incompressible flow, combining with the finite volume method (FVM) to discretize calculation domain, a modified VOF method to track the free surface, and a k−ε model to closure the turbulence. The nearshore sediment transport process is reproduced in view of shear stress, suspended load, and bed load, in which the terms of shear stress and suspended load were updated by introducing volume fraction. The seabed morphology is updated based on Exner equation and implemented by dynamic mesh technique. The mass conservative sand slide algorithm was employed to avoid the incredible vary of the bed mesh. Importantly, a two-way coupling method connecting the hydrodynamic module with the beach morphodynamic module is implemented at each computation step to ensure the fluid-sediment interaction. The capabilities of this model were calibrated by laboratory data from some published references, and the advantages/disadvantages, as well as proper recommendations, were introduced. Finally, nonbreaking- and breaking wave-induced scour around the monopile, as well as breaking wave-induced beach evolution, were reproduced and discussed. This study would be significantly helpful to understand and evaluate the nearshore sediment transport.

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CFD modeling of scale effects on turbulence flow and scour around bridge piers

Cited by 62 publications

References 11 publications

Scale effects in physical hydraulic engineering models

Scale effects in physical hydraulic engineering models

Streamlining of Bridge Pier as a Scour Countermeasure: A Feasibility Study

3D Modeling and Mechanism Analysis of Breaking Wave-Induced Seabed Scour around Monopile

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