检索结果-南通市图书馆

维普期刊数据库

Particle size distribution of bed materials in the sandy river bed of alluvial rivers

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2017年第3期32卷 331-339页

作者： Luohao Zhang Hongwu Zhang Hongwu Tang Chensu Zhao College of Water Conservancy and Hydropower Engineering Hohai University State Key Laboratory of Hydroscience and Engineering Tsinghua University School of Civil and Environment Engineering University of Science and Technology Beijing

The particle size distribution of bed materials in the sandy river bed of alluvial rivers is important in the study of topics such as friction, river bed evolution, erosion, and siltation. It also can reflect the dependency relation between river bed sediment and flow intensity. In this paper, the critical pattern of sediment movement in the near-wall region of a sandy river bed was analyzed. According to the principle of momentum balance, the critical settling-rising condition of bed material in a sandy river bed was found to be instantaneous turbulent velocity equal to 2.7 times the sediment settling velocity in quiescent water. Based on a vertical instantaneous turbulent velocity with a Gaussian distribution, a theoretical relation for calculating the particle size distribution of bed materials in a sandy river bed without pre-known characteristic grain sizes was developed by solving a stochastic equation. The formula is verified using measured data, and the results show that the proposed formula was in accordance with the measured data. This study has theoretical significance and practical value for determining the bed material particle size distribution of the sandy bed of alluvial rivers.

关键词： Particle size distribution bed material Turbulence Momentum Sandy river bed

Study of deposition of fine sediment within the pores of a coarse sediment bed stream

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2013年第2期28卷 210-219页

作者： N.K.KHULLAR U.C.KOTHYARI K.G.Ranga RAJU Department of Civil Engineering PAU Ludhiana-India Prof.Dr. Department of Civil Engineering IIT Roorkee-India Prof.Dr. Department of Civil Engineering IIT Roorkee-India Formerly Prof.Dr.

Elaborate experiments were performed in a 30 m long,0.5 m deep and 0.2 m wide laboratory flume to study the process of infiltration of fine sediment into the pores of coarse sediment forming the channel bed *** concentrations of suspended load of fine sediment of size 0.064 mm were passed over the channel bed made up of three different types of coarse sediments;two uniform and one *** proportion of fine sediment infiltrated into the pores of bed material for each equilibrium concentration of suspended load of fine sediment in the flow was studied during several experimental *** proportion of fine sediment within the pores of bed material increased with an increase in the equilibrium concentration of suspended load of fine sediment in the *** process continued till the pores within the coarse sediment bed were filled up to the capacity with the fine sediment transported by the flow in *** theoretical value was identified for limit for maximum proportion of fine sediment that can be present within the pores of bed *** further increase in the concentration of suspended load of fine sediment in the flow,deposition of fine sediment occurs on the surface of the flume bed in the form of ripples of the fine *** condition is defined as ’depositional condition’.Experimental observations on these and related aspects are presented herein.

关键词： Fine sediment Flume experiment bed material Concentration of suspended sediment Deposition condition

SCOUR OF FINE SEDIMENT BY A TURBULENT WALL JET

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1994年第4期6卷 93-96页

作者： Li Wen-xue (Institute of Hydraulic Research, Yellow River Conservancy Commission, Zhengzhou, 450003, P. R. ChinaSupervisor: Prof. Peter A. Mantz, Ph. D.)(Lamar University , P. O. Box 10024, Beaumont, Texas 77710, U. S. A.)

A total of 66 experiments were conducted to investigate the scour of fine finesediment by a turbulent wall jet. The independent variables studied were the flow velocity, the jet size, the grain sine, and the water *** Closely sized grades of bed material were used, and their median diameters were 0. 273mm, 0. 050mm, and 0. 030mm. The jet velocities varied from 0. 30m/s to 1. 10m/s for the coarse sediment (D =0. 273mm), and from 0. 30m/s to 0. 70m/s for the fine grades (D = 0. 050mm , and D= 0. 030mm). The jet size was set to 3. 18mm, 6, 35mm, and 9. 53mm for each grade size, and the water temperature varied from about 60 degrees Fahrenheit to about 85 degrees *** independent variables were analyzed using dimensional analysis. Three dimentsionless Parameters, namely U(=pu2/ΔpgD), B(b/D), and G(=ΔpgD3/pv2), were obtained. These parameters enabled a close correlation of all experimental results. Other studies were also found to correlate well with these parameters.

关键词： turbulent wall jet scour hole machine vision bed material edgetracking,bed profile.

维普期刊数据库

CRITICAL CONDITION FOR THE INITIATION OF SUSPENSION

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 1993年第3期 51-69页

作者： CHENG Niansheng and ZHU Lijun Senior engineer, Nanjing Hydraulic Research Institute, China Engineer, Nanjing Hydraulic Research Institute, China

Channel bed deformation and sediment transport result from the exchanges among various forms of sediment movement. It is significant to take into account the interactions of suspended load, bed load and movable bed to explore the mechanism of bed changes and develop better modelling methods. Considering the influences of the near-bed turbulence on the critical condition of suspending processes of sediment particles, theoretical criterion is presented according to the concept of probability of suspension. In addition, several existing formulae are thus analysed and compared with each other.

关键词： Suspension bed load suspended load near-bed turbulence bed material Viscous sublayer burst phenomena probability.

A MATHEMATICAL MODEL FOR RESERVOIR SEDIMENTATION AND FLUVIAL PROCESSES

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 1990年第2期 43-84页

作者： Han Qiwei and He Mingmin (Senior Research Engineers, Dept. of Sedimentation Eng. Inst. of Water Conservancy and Hydroelectric Power Research.) (The English text is abridged, altered and edited by Ding Lianzhen)

This paper consists of two parts: mechanism of non-equilibrium transport of non-uniform sediment and its application in the mathematical model. Based on a statistic approach of sediment transport proposed by the authors, a 1 - D equation of non-e- quilibrium transport for various size group of sediment particles is developed. Then equations to predict change of sediment concentration and the corresponding changes in size distribution of suspended load and bed material are also derived. The conception that changes in size distribution are interrelated to sediment-carrying capacity is expounded. These results reveal the essence of sediment transport of non-uniform sediment particles. In the second part a mathematical model incorporating the mentioned equations to compute deposition and scouring in reservoirs as well as the fluvial processes of river channels has been developed. Verification of the model agrees well with field data.

关键词： Mathematical model Non-equilibrium sediment transport Sediment-carrying capacity Reservoir sedimentation Fluvial process Size distribution bed material Scouring Deposition Exchange intensity Consolidation of deposit.