Mechanisms of particle vertical diffusion in sediment-laden flows  

作　　者：WANG Guangqian FU Xudong Key Lab for Water and Sediment Sciences of Ministry of Education, Tsinghua University, Beijing 100084, China Correspondence should be addressed to Wang Guanqian 

出　　处：《Chinese Science Bulletin》2004年第10期1086-1090,共5页

摘　　要：Diffusion coefficient of natural sediments andeffects of lift force and gradient in particle velocity fluctua-tions were investigated through using a closed kinetic model.Comparison against experimental data of Einstein ＆ Chien(1955) validated the model. The diffusion coefficient εyy ofmedium and large sediments distinctly exceeds fluid eddyviscosity V^tf, while εyy of fine sediments approximately equals V^tf. In the measured region of 0.03＜y/H＜0.4, εyy/V^tf increaseswith the distance from the wall decreasing. Combined effectsof lift force and gradient in particle velocity fluctuationschange sediment gravitational settling remarkably below y/H=0.2, and need to be accounted for describing sedimentdiffusion in this region.Diffusion coefficient of natural sediments andeffects of lift force and gradient in particle velocity fluctua-tions were investigated through using a closed kinetic model.Comparison against experimental data of Einstein & Chien(1955) validated the model. The diffusion coefficient ε_(yy) ofmedium and large sediments distinctly exceeds fluid eddyviscosity v_f^t, while ε_(yy) of fine sediments approximately equalsv_f^t.In the measured region of 0.03<y/H<0.4, ε_(yy)/v_f^t increaseswith the distance from the wall decreasing. Combined effectsof lift force and gradient in particle velocity fluctuationschange sediment gravitational settling remarkably belowy/H=0.2, and need to be accounted for describing sedimentdiffusion in this region.

关 键 词：沉积物 两相流 动力模型 扩散效率 升力 

分 类 号：P512.2[天文地球—地质学]