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Diffusion Characteristic of Floating Particles in Vegetated Open Channel Flow

Author(s): Xiaoguang Liu; Yuhong Zeng; Jiasheng Wang; Zhaohui Chai

Linked Author(s): Yuhong Zeng

Keywords: No keywords

Abstract: Advection-diffusion models have been widely applied to describe the transport of particles through vegetation with assuming that the particle transport is driven by the mean flow velocity, and few studies on the diffusion process with considering the retention time. In this study, the authors conduct flume experiments of four runs with different vegetative densities, extract and analyze the trajectories of floating particles. Retention time of trapping events due to the capillary between particles and the stem has been proved to follow a three-parameter double exponential distribution, duration time of both short and long retention events increases with the bulk flow velocity increasing, and the proportion of long-time trapping events decreases with the bulk flow velocity increasing. The transport velocity of floating particles is considered to be decided by the constricted cross-section velocity and temporary trapping events. The diffusion coefficient of floating particles is validated independent of vegetative densities and increases with the flow velocity increasing, and which is about 100 times that of the solute in flow through emergent vegetation under similarity condition.


Year: 2022

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