Wang Feifei, Li Zhiwei, Huai Wenxin
School of Water Conservancy and Engineering, Zhengzhou University, Zhengzhou, 450001, China.
State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, 430072, China.
Environ Sci Pollut Res Int. 2022 Oct;29(46):70099-70113. doi: 10.1007/s11356-022-20833-7. Epub 2022 May 18.
There is a need for developing efficient models to simulate the sediment transport phenomenon in ice-covered alluvial channel flows, which is essential in enriching the theory of riverbed evolution. This study establishes a random displacement model parameterized with the time-averaged streamwise velocity U(z), the sediment settling velocity ω(z), and the turbulent diffusion coefficient D(z) to calculate the suspended sediment concentration and the longitudinal dispersion coefficient for ice-covered alluvial channels. The proposed model is first validated to determine if it could be used to predict the sediment concentration profiles by comparing to limited experiments published in the literature. Results show that the simulations agree well with the measurements except for the underestimated concentration near the ice cover boundary. Once validated, the random displacement model is applied to explore the variation law of the suspended sediment concentration and the longitudinal dispersion with different sediment particle release modes. The sediment concentration and the stable value of the longitudinal dispersion coefficient for a given flow condition in the dynamic equilibrium state are not affected by the change of the particle release mode. The Fickian time required for the longitudinal dispersion coefficient converging to a constant, however, has a close relationship with the particle release mode and increases as the water depth increases.
需要开发高效的模型来模拟冰封冲积河道水流中的泥沙输移现象，这对于丰富河床演变理论至关重要。本研究建立了一个以时间平均流向速度U(z)、泥沙沉降速度ω(z)和紊流扩散系数D(z)为参数的随机位移模型，用于计算冰封冲积河道的悬沙浓度和纵向扩散系数。首先通过与文献中发表的有限实验进行比较，对所提出的模型进行验证，以确定其是否可用于预测泥沙浓度剖面。结果表明，除了冰盖边界附近浓度被低估外，模拟结果与测量值吻合良好。一旦验证通过，随机位移模型就被用于探索不同泥沙颗粒释放模式下悬沙浓度和纵向扩散的变化规律。在动态平衡状态下，给定水流条件下的泥沙浓度和纵向扩散系数的稳定值不受颗粒释放模式变化的影响。然而，纵向扩散系数收敛到常数所需的菲克时间与颗粒释放模式密切相关，并随水深增加而增加。
