Numerical investigation of particle saltation in the bed-load regime  

作　　者：JI ChunNing ANTE Munjiza ELDAD Avital XU Dong JOHN Williams 

机构地区：[1]State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University [2]School of Engineering & Materials Science,Queen Mary,University of London

出　　处：《Science China(Technological Sciences)》2014年第8期1500-1511,共12页中国科学（技术科学英文版）

基　　金：supported by a Marie Curie International Incoming Fellowship within the seventh European Community Framework Programme(Grant No.PIIF-GA-2009-236457);the financial support of the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.51321065);Programme of Introducing Talents of Discipline to Universities(Grant No.B14012);National Natural Science Foundation of China(Grant Nos.50809047 and 51009105);Natural Science Foundation of Tianjin(Grant No.12JCQNJC02600)

摘　　要：This paper numerically investigates particle saltation in a turbulent channel flow having a rough bed consisting of 2–3 layers of densely packed spheres.In this study,we combined three the state-of-the-art technologies,i.e.,the direct numerical simulation of turbulent flow,the combined finite-discrete element modelling of the deformation,movement and collision of the particles,and the immersed boundary method for the fluid-solid interaction.Here we verify our code by comparing the flow and particle statistical features with the published data and then present the hydrodynamic forces acting on a particle together with the particle coordinates and velocities,during a typical saltation.We found strong correlation between the abruptly decreasing particle stream-wise velocity and the increasing vertical velocity at collision,which indicates that the continuous saltation of large grain-size particles is controlled by collision parameters such as particle incident angle,local rough bed packing arrangement,and particle density,etc.This physical process is different from that of particle entrainment in which turbulence coherence structures play an important role.Probability distribution functions of several important saltation parameters and the relationships between them are presented.The results show that the saltating particles hitting the windward side of the bed particles are more likely to bounce off the rough bed than those hitting the leeside.Based on the above findings,saltation mechanisms of large grain-size particles in turbulent channel flow are presented.

关 键 词：particle saltation bed-load regime hydrodynamic forces turbulent channel flow 

分 类 号：TV149[水利工程—水力学及河流动力学]