Abstract
Diffusion coefficient of natural sediments and effects of lift force and gradient in particle velocity fluctuations were investigated through using a closed kinetic model. Comparison against experimental data of Einstein & Chien (1955) validated the model. The diffusion coefficient εyy of medium and large sediments distinctly exceeds fluid eddy viscosityv tf , while εyy of fine sediments approximately equalsv tf . In the measured region of0.03<y/H<0.4, ε yy/v tf increases with the distance from the wall decreasing. Combined effects of lift force and gradient in particle velocity fluctuations change sediment gravitational settling remarkably belowy/H=0.2, and need to be accounted for describing sediment diffusion in this region.
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Wang, G., Fu, X. Mechanisms of particle vertical diffusion in sediment-laden flows. Chin. Sci. Bull. 49, 1086–1090 (2004). https://doi.org/10.1007/BF03184041
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DOI: https://doi.org/10.1007/BF03184041