Incipient motion of non-uniform coarse grain of bedload considering the impact of two-way exposure  

作　　者：BAI YuChuan WANG Xin CAO YongGang 

机构地区：[1]State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University [2]Institute for Sedimentation on River and Coastal Engineering,Tianjin University [3]South China Sea Marine Engineering Surveying Center,SOA

出　　处：《Science China(Technological Sciences)》2013年第8期1896-1905,共10页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 51279124,51021004,50979066)

摘　　要：The incipient motion of bedload is due to the interaction between the flow and sediment.It is stochastically correlated with the flow structure,the sediment gradation and the arrangement of grains on the bed surface.The random position of the sediment on bed can be represented by a hiding factor or an exposure degree.Based on the numerical simulation of the disturbed flow in the interstice of grains,the influence of the two-way exposure degree(the vertical exposure degree and the longitudinal exposure degree) on the coarse grain incipient motion was investigated in this work.Results show that the exposure degree varies with the position of the sediment on the bed,which influences the flow structure around the particle and the incipient motion.In this paper,the major research achievements on this phenomenon include:Firstly,a mathematical model is established for the rolling-pattern incipient motion of the coarse grain under a critical state of moment balance.The influence of the partial disturbed flow is considered.Secondly,the two-way relative-exposure-degree probability distribution functions are developed to reflect the influence of the disturbed flow and the random arrangement of sediments.Thirdly,a formula to calculate the incipient velocity is presented based on the above results,which considers the impact of the two-way exposure degree of sediment particles.

关 键 词：coarse grain of bedload exposure degree rolling incipient model moment equilibrium incipient velocity 

分 类 号：TV142[水利工程—水力学及河流动力学]