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EXPERIMENTAL STUDY ON BED SHEAR STRESS AND SEDIMENT TRANSPORT IN A meandering LABORATORY channel

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International Journal of Sediment Research 2002年第1期17卷 1-19页

作者： L. YILMAZ1, Vijay P. SINGH2, S.K. MISHRA3, D. D. ADRIAN2 and J. J. SANSALONE2 1 Civil Engineering Faculty, Hydraulic Division, Technical University of Istanbul, 80626, Maslak, Istanbul, Turkey Civil Engineering Faculty Hydraulic Division Technical University of Istanbul 80626 Maslak Istanbul Turkey Dept. of Civil and Environmental Engineering Louisiana State University Baton Rouge LA 70803-6405 U. S. A. National Institute of Hydrology Roorkee-247 667 Uttaranchal India

An experimental study was carried out to investigate bed shear stress of a flow boundary layer with meandering features and sediment transport in a meandering channel. By measuring the shear stress distribution with hot-film sensors, the stability of the fluid-bed interface and the characteristics of the bed features were investigated experimentally in a laboratory model for free-surface flow over an erodible bed. The experimental results are presented in two parts. First, experimental observations of meander evolution due to inhomogeneous distribution of boundary layer meander features are qualitatively described in terms of the shear stress distribution. Second, an empirical relation is proposed for the shear stress distribution measured with WTG-50 hotfilmanemometer at the wavy iron bed. The sediment transport rate measured in the meandering channel in a laboratory flume was used to evaluate and compare the sediment transport formulae of Shield (1936), Meyer-Peter and Mller (1948), Einstein (1950), and Bagnold (1966). The sedimentation rates computed using these formulae were found to be generally higher than those observed in the laboratory. However, the Einstein formula yields these rates closest to the measured ones but with an over-prediction of 64.5% in general. Using the experimental observations, empirical formulae were also developed for predicting the sediment transport rate and the meander planforms for a specific condition.

关键词： Bed shear stress Sediment transport meandering channel Stability Boundary layer

Numerical model of flow and pollutant transportation in non-orthogonal curvilinear coordinates

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Journal of Environmental Sciences 2004年第2期16卷 293-296页

作者： WUXiu-guang SHENYong-ming ZHENGYong-hong YANGZhi-feng StateKeyLaboratoryofCoastalandOffshoreEngineering DalianUniversityofTechnologyDalian116024China. GuangzhouInstituteofEnergyConversion ChineseAcademyofSciencesGuangzhou510070China InstituteofEnvironmentalScience BeijingNormalUniversityBeijing100875China

The planar 2D k-ε double equations' turbulence model was adopted and transformed into non-orthogonal curvilinear coordinates. The concentration convection-diffusion was introduced to planar 2D SIMPLEC algorithm of flow in non-orthogonal curvilinear coordinates. The numerical model of pollutant transportation in non-orthogonal curvilinear coordinates was constructed. The model was applied to simulate the flow and pollutant concentration fields. In the testing concentration field, two optimal operations of contamination discharging both along bank and in the centerline at the first bend of the meandering channel were adopted. Comparison with available data showed the model developed was successful, was valuable to engineering application.

关键词： curvilinear coordinates diffusion-transportation SIMPLEC algorithm concentration fields meandering channel

Assessment of the predictive capability of RANS models in simulating mean-dering open channel flows

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Journal of Hydrodynamics 2017年第1期29卷 40-51页

作者：周建银邵学军王虹假冬冬 Key Laboratory of River Regulation and Flood Control of MWR Changjiang River Scientific Research InstituteWuhan 430010China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210029China

The predictive capability of Reynolds-averaged numerical simulation （RANS） models is investigated by simulating the flow in meandering open channel flumes and comparing the obtained results with the measured data. The flow structures of the two experiments are much different in order to get better insights. Two eddy viscosity turbulence models and different wall treatment methods are tested. Comparisons show that no essential difference exists among the predictions. The difference of turbulence models has a limited effect, and the near wall refinement improves the predictions slightly. Results show that, while the longitudinal velo- cities are generally well predicted, the predictive capability of the secondary flow is largely determined by the complexity of the flow structure. In Case 1 of a simple flow structure, the secondary flow velocity is reasonably predicted. In Case 2, consisting of sharp curved consecutive reverse bends, the flow structure becomes complex after the first bend, and the complex flow structure leads to the poor prediction of the secondary flow. The analysis shows that the high level of turbulence anisotropy is related with the boundary layer separation, but not with the flow structure complexity in the central area which definitely causes the poor prediction of RANS models. The turbulence model modifications and the wall treatment methods barely improve the predictive capability of RANS models in simulating complex flow structures.

关键词： RANS model secondary flows boundary layer separation turbulence model meandering channel near-wall treatment

MODELING OF RIVER MORPHOLOGIC CHANGES

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International Journal of Sediment Research 1995年第2期 1-20页

作者： Charles C. S. SONG Yifan ZHENG and Chih Ted YANG( , St. Anthony Falls Hydraulic Laboratory, Department of Civil Engineering, University of Minnesota, Minneapolis MN 55414, U. S. A.)( Bechtel Corporation, formerly Reseaxch Assistant, St. Anthony Falls H

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关键词： Bank stability channel geometry Flood Local scour meandering channel Minimum energy dissipation rate Numerical model River Morphology Sediment transport

Effect of Meander on Bridge Pier Scour

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Hydro Science & Marine Engineering 2021年第2期3卷 20-31页

作者： M.Athar M.K.Sabiree H.Athar Civil Engineering Department A.M.U.AligarhU.P.India U.P.Irrigation DepartmentU.P.India C.B.R.I. RoorkeeUttarakhandIndia

have been done in the past by many researchers.Many factors which affect scour around piers such as shape of piers,size,positioning and orientation etc.have been studied in detail by them.However,similar studies in meandering channels are scanty.Very few researchers have studied the effect of angular displacement which has considerable effects of scour around bridge piers.In this paper an attempt has been made to carry out a detailed study of angular displacement on scour.A constant diameter bridge pier of circular shape has been tested in a meandering channel bend with bend angle as 800.The test bed was prepared by using uniform sand having d50 as 0.27 mm and run was taken for a discharge of 2.5 l/s.

关键词： meandering channel Angular displacement Scour and deposition Bridge piers Inner bank and outer bank

Computing Depth-averaged Flows Using Boundary-fitted Coordinates and Staggered Grids

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Tsinghua Science and Technology 2000年第2期5卷 226-230页

作者：洪益平周雪漪陈永灿余常昭 Department of Hydraulic and Hydropower Engineering Tsinghua University Beijing 100084 China

A depth averaged nonlinear k ε model for turbulent flows in complex geometries has been developed in a boundary fitted coordinate system. The SIMPLEC procedure is used to develop an economical discrete method for staggered grids to analyze flows in a 90° bend. This paper describes how to change a program in rectangular coordinate into a boundary fitted coordinate. The results compare well with experimental data for flow in a meandering channel showing the efficiency of the model and the discrete method.

关键词： depth-averaged k-ε model boundary-fitted coordinates staggered grid meandering channel

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下荆江人工裁弯30年

人民长江 2002年第Z1期33卷 40-45页

作者：潘庆燊 Professor-senior Engineer Yangtze River Scientific Research Institute Changjiang Water Resources Commission Wuhan 430010 China

River cutoff works have been implemented on Lower Jingjiang section for 30 years. Engineering practices have shown that channel straightening has been the river regulation measure for the permanent control of the meandering Lower Jingjiang section. River cutoff have been carried out in accordance with the evolution property of meandering rivers and these works have brought about expected benefits. It has also been noted that certain aspects in river cutoff had not been fully understood. River cutoff is a dynamic engineering. River channel evolution properties shall be fully understood so as to adroitly guide actions according to circumstances in cutoff works. In addition, river channel evolution observation and engineering effectiveness monitoring should be strengthened with a view to update the designs. The diversion canals for channel shortening are of great importance that will account for the success or failure of river cutoff works. The newly formed river channels and the river regime control works on the adjacent upper and lower reaches are guarantees for river cutoff works to be brought into play in the long run.

关键词： river cutoff works river regime control river training meandering channel Lower Jingjiang section of Changjiang River