Shear Stress around Vertical Wall Abutments

Molinas, Albert; Kheireldin, Khaled; Wu, Baosheng

doi:10.1061/(asce)0733-9429(1998)124:8(822)

Cited by 48 publications

(31 citation statements)

References 5 publications

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“…Previous studies have shown that at the tips of the deflectors, turbulence, vortices (horseshoe vortex system), downflows, and bed shear stress are intensified (Rajaratnam and Nwachukwu, 1983;Molinas et al, 1998). Ahmed and Rajaratnam (1998) observed smaller shear stress amplification over a smooth bed compared to a rough bed near an obstacle.…”

Section: Discussionmentioning

confidence: 92%

“…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: 99%

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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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Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Three-dimensional flow dynamics around deflectors

et al. 2005

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“…In order to test and verify the computational model, a series of laboratory experiments conducted at the Colorado State University (CSU) Hydraulics Laboratory to study velocity and shear stress distribution around vertical wall abutments were used (Kheireldin 1995;Molinas, Kheireldin & Wu 1998). Additional veri"cations were provided through comparisons with experiments conducted to study #ow around groins which can be visualized as very thin abutments (Rajaratnam & Nwachukwu 1983).…”

Section: Model Verificationmentioning

confidence: 99%

Finite Element Surface Model for Flow Around Vertical Wall Abutments

Molinas

Hafez

2000

Journal of Fluids and Structures

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“…In the past several decades, many studies have been conducted by people such as Melville (1992), (Molinas and Wu, 1998), (Dey and Barbhuiya, 2005) and Melville et al (2006), to identify the mechanism, scour development and scour phenomenon around the abutment. Methods of scour reduction have been analyzed by various researchers, each of which has advantages and disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Effect of Collar and Roughness on Reducing and Controlling the Local Scour around Bridge Abutment

Shahsavari

Heidarpour

Mohammadalizadeh

2017

Acta Univ. Agric. Silvic. Mendelianae Brun.

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Investigation of local scour around hydraulic structures particularly bridges is of crucial importance in river engineering. Bridge destruction mostly occurs as a result of scour phenomenon around piers and abutments, not because of structural weaknesses. Hence, finding a solution to reduce scour depth is momentous. In this study which was conducted in the conditions of clear water scour, the effect of local roughness and collar and also impact of using them simultaneously around bridge abutment were evaluated. The results demonstrated that the existence of roughness causes a reduction in the severity of scouring process and its final depth and the use of collar leads to a delay in the scouring process in addition to the ultimate reduction in the scour depth, which in case of using them simultaneously, scour depth decreases by about 83%.

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Shear Stress around Vertical Wall Abutments

Cited by 48 publications

References 5 publications

Three-dimensional flow dynamics around deflectors

Three-dimensional flow dynamics around deflectors

Finite Element Surface Model for Flow Around Vertical Wall Abutments

Simultaneous Effect of Collar and Roughness on Reducing and Controlling the Local Scour around Bridge Abutment

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