Finite Element Surface Model for Flow Around Vertical Wall Abutments

Molinas, Albert; Hafez, Youssef I.

doi:10.1006/jfls.2000.0295

Cited by 15 publications

(16 citation statements)

References 13 publications

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“…Most literature, however, foc uses on the length o f the dow nstream recirculation zone, and thus v ery little attention has been paid to the size and shape of the upstream separation zone (Molinas and Hafez, 2000). As a result, there are few avai lable examples for comparison with our observed Fs and Fw values.…”

Section: Discussionmentioning

confidence: 64%

“…This may pote nti ally be a result of the ' pixelation' of the deflectors, as the noses of the angled obstructions in the model are not square (as they are in the flume). Rather, the effective lengthening of the deflector in the stream wise direction may have fl ow straightening effects (Molinas and Hafez, 2000), which in turn would explain the reduction in lateral extent observed in the simulated recirculation zone.…”

Section: Evaluation Of Model Predictions Against Laboratory Datamentioning

confidence: 98%

See 1 more Smart Citation

Three-dimensional numerical simulation of flow around stream deflectors: The effect of obstruction angle and length

Haltigin

Biron

Lapointe

2007

Journal of Hydraulic Research

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Section: Discussionmentioning

confidence: 64%

Section: Evaluation Of Model Predictions Against Laboratory Datamentioning

confidence: 98%

Three-dimensional numerical simulation of flow around stream deflectors: The effect of obstruction angle and length

Haltigin

Biron

Lapointe

2007

Journal of Hydraulic Research

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“…The groyne used was an aluminum plate of thickness of 3 mm and length, b = 0.15 m. Details of the experiment can be found in Rajaratnam and Nwachukwu (1983). The results of the same experiment were also used by Tingsanchalli and Maheswaran (1990), Molls and Chaudhry (1995) and Molinas and Hafez (2000) to verify their predictions. Tingsanchalli and Maheswaran (1990) used a depth-averaged flow model and the k − ε turbulence model to compute the velocity and bottom shear stresses in the vicinity of the groyne.…”

Section: Test Problem: Flow Near Groyne-like Structuresmentioning

confidence: 99%

“…Molls and Chaudhry (1995) presented a mathematical model to solve the unsteady, depth-averaged equations with the turbulent stresses obtained from Boussinesq's eddy-viscosity concept. Molinas and Hafez (2000), on the other hand, used a 2D finite element model to determine the velocities and the turning angles around vertical wall abutments. The eddy viscosity in that study was determined by using the depth-averaged turbulent viscosity formulation of Rastogi and Rodi (1978).…”

Section: Test Problem: Flow Near Groyne-like Structuresmentioning

confidence: 99%

Prediction of Bank Erosion in a Reach of the Sacramento River and its Mitigation with Groynes

Ercan

Younis

2009

Water Resour Manage

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The paper reports on the prediction of flow in a reach of the Sacramento River with focus on a part of the river's bank where serious erosion has occurred. The simulations were obtained using a three-dimensional Navier-Stokes solver which utilized body-fitted coordinates to represent the complex river bathymetry. Comparative predictions were obtained using a two-dimensional, depth-averaged formulation. Local (nested) mesh refinement was employed to provide the necessary resolution of the bank geometry in the region of interest. The study focuses on the assessment of the effectiveness of a particular arrangement of groynes which was found in physical model studies to significantly reduce the rate of erosion in the region under consideration. To validate the computational models, predictions were first obtained for the case of turbulent flow in a straight rectangular channel with one groyne. Measurements of velocity and boundary shear stress were used for model validation. For the reach of the Sacramento River under consideration, velocity measurements obtained in the large-scale physical model were also used to check the computational model prior to its use for prediction of the river flow with groynes. Here, too, both depth-averaged and three-dimensional computations were performed with the objective being to determine the influence of the groynes on the flow velocity. The bank erosion rate was estimated by coupling the 'excess shear stress' method to the computed mean velocity field. The results show that for the groynes configuration that was found optimal in the physical-model studies, and that was actually implemented in the Sacramento River, the groynes are effective in reducing the bank erosion of the affected zone but at the cost of transferring a far less severe problem further downstream.

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“…Most of the literature on flow dynamics around instream structures has focused on bridge piers (Ahmed and Rajaratnam, 1998;Sarker, 1998;Graf and Istiarto, 2002) and abutments (Molinas et al, 1998;Ahmed and Rajaratnam, 2000;Molinas and Hafez, 2000;Chrisohoides et al, 2003). Although there are similarities between these structures and deflectors, from an engineering point of view, the objective is to limit scouring whereas the objective of deflectors is to promote it.…”

Section: Introductionmentioning

confidence: 98%

Three-dimensional flow dynamics around deflectors

et al. 2005

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Many river rehabilitation projects to enhance the aquatic habitat focus on the creation of pool and riffle habitat by the implementation of flow deflectors, with various degrees of successes and failures. A more comprehensive understanding of the complex three-dimensional flow dynamics that induces scour around instream structures is required for a more effective design. The objective of this study is to examine the three-dimensional mean and turbulent flow characteristics around paired flow deflectors for various types of deflector design in a laboratory flume. Three deflector angles (45 , 90 and 135 ) and two deflector heights (with flow under and over the deflector height) were tested over a smooth (plexiglas) bed and a sand bed. Three-dimensional velocity measurements were taken with an acoustic Doppler velocimeter at several planform positions at two heights above the bed. Results show that the 90 deflectors create the most important disturbance in the mean flow field, in turbulence intensity and bed shear stress. There is, however, a marked difference in the spatial distribution of the mean and turbulent parameters over a mobile bed and over a smooth, fixed bed. This stresses the importance of understanding the feedback between bed topography and flow dynamics and limits the applicability of conclusions drawn from plane bed experiments to natural rivers.

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Finite Element Surface Model for Flow Around Vertical Wall Abutments

Cited by 15 publications

References 13 publications

Three-dimensional numerical simulation of flow around stream deflectors: The effect of obstruction angle and length

Three-dimensional numerical simulation of flow around stream deflectors: The effect of obstruction angle and length

Prediction of Bank Erosion in a Reach of the Sacramento River and its Mitigation with Groynes

Three-dimensional flow dynamics around deflectors

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