Near-bed hydrodynamics associated with the entrainment of coarse particles at different protrusion heights  

作　　者：Yushu Xie Bruce W.Melville Asaad Y.Shamseldin Colin N.Whittaker Yifan Yang 

机构地区：[1]Department of Civil and Environmental Engineering,The University of Auckland,Auckland,New Zealand [2]School of Engineering,The University of Waikato,Hamilton,New Zealand

出　　处：《Journal of Hydrodynamics》2022年第6期1067-1080,共14页水动力学研究与进展B辑（英文版）

基　　金：the financial support of the Chinese Scholar Council(CSC)and The University of Auckland.

摘　　要：This paper presents an investigation of near-bed hydrodynamics for a protruding coarse particle over a regular roughened bed.The laboratory experiments were undertaken at the threshold flow condition,which induced dislodgement of the protruding particle.Using different protrusion heights,the experimental results show that the protruding particle substantially changed the spatial distributions of time-averaged velocities,turbulent kinetic energy,and Reynolds shear stress when compared with those obtained from a flat rough bed.The spatial distribution pattern of the flow characteristics shows a reasonable degree of similarity at different protrusion heights examined in this study.Above the target particle,a zone of low Reynolds shear stress was observed.Quadrant analysis was conducted along the main flow direction,at an elevation close to the top of the target particle.A prevalence of sweep(Quadrant 4)and outwards interaction(Quadrant 1)events were associated with the dislodgement of the protruding particle.These findings imply that the drag force related to strong streamwise velocities may play a more significant role in protruding particle entrainment than the shear stress.

关 键 词：ENTRAINMENT particle protrusion flow structure shear stress quadrant analysis 

分 类 号：O352[理学—流体力学] P756.8[理学—力学]