汇流比对U形弯曲交汇河道中污染物离散系数的影响

The influence of discharge ratio on the pollutant dispersion coefficient in the U-shaped confluent curved river

针对弯曲河道交汇区污染物离散系数的分布特征进行研究,通过建立U形弯曲交汇河道水气两相流数学模型,进行交汇区水动力数值模拟。数学模型经试验数据验证后,模拟分析了不同汇流比对弯道交汇区水流结构和离散特性的影响,离散系数采用二维离散张量法进行计算。结果表明,支流入汇导致交汇断面附近纵向和横向离散系数达到峰值,该峰值随着汇流比的增大而增大;横向离散系数沿程分布呈现单峰结构,纵向离散系数沿程分布呈现双峰结构。

The distribution characteristics of pollutant dispersion coefficient in the confluence of a curved river with tributary are studied. The mathematical model of air-water two-phase flow in the U-shaped confluent channel is established and verified by the data of previous laboratory experiments. Based on the simulation results,the influence of different discharge ratio on the flow structure and dispersion characteristics of confluent curved river is analyzed,in which the dispersion coefficient is calculated by the two-dimensional tensor method. The results show that the dispersion coefficient reaches the peak value in the vicinity of convergence,and the peak value increases with the increase of discharge ratio. Moreover, the longitudinal dispersion coefficient shows a single peak distribution along the river,while the transversal dispersion coefficient presents a double-peak structure.