基于POMgcs的复式断面河道纵向离散系数研究

Study on Longitudsinal Dispersion Efficient of Compound Channel Based on POMgcs Model

天然河流中广泛存在由主槽、滩地构成的复式河道的水污染问题,纵向离散系数是河流水质预测的关键参数。通过建立三维数学模型,对物理水槽试验的流速分布特征进行验证,得到不同滩槽高差、水深条件下的纵向离散系数。基于复式断面各区域流速差异较大的特征,将断面划分为主槽中心区、滩地区和主槽底部区,由纵向离散系数与流速差异系数、断面几何参数的相关性分析,同时引入弗劳德数,建立了复式断面纵向离散系数计算公式。计算结果表明:公式计算值与模型计算值相对平均误差在10%以内,具有一定可靠性。

Aiming at the water pollution problem of natural rivers which is made up of main channel and beach,the longitudinal dispersion coefficient is the key to the prediction of river water quality.By establishing a mathematical model and verifying the characteristics of velocity distribution,the characteristics of pollutant distribution and longitudinal dispersion coefficient under different beach height differences and water depths were obtained.Based on the characteristics of the large difference of regional velocity in the composite section,the section was divided into the central area of the main channel(Ⅰ),the beach area(Ⅱ)and the bottom area of the main channel(Ⅲ).The correlation between the shape of the section and the velocity difference was analyzed.At the same time,the formula of longitudinal discrete coefficient of compound channel was established by introducing Frode number Fr.The calculation results show that the error of the formula is less than 10%,which has a certain reliability of engineering application.