梯形渠道岸边排污浓度分布的理论分析

从无限区域圆形瞬时源扩散的浓度分布公式人手,推导出梯形区域内瞬时线源扩散的近似浓度计算公式,进而得到了梯形渠道岸边排污的浓度分布公式计算公式表明,边坡倾角对污染物的浓度分布影响较大,浓度值随边坡倾角的增加而减小,近似遵循双曲线的递减规律.浓度分布解析解得到了扩散方程数值解的良好验证,两者在污染源附近有所差异,但随着距污染源距离的增加,计算结果愈加吻合,该解析公式可为天然河流岸边污染混合区的污染物浓度估算提供有力的工具.

Analytical solution to concentration distribution discharged from a stream of effluent into trapezoidal channel flow

An analytical solution is presented to determined the distribution of concentration in a trapezoidal channel due to a stream of effluent discharging. Based on the concentration distribution around an instantaneous circle source, the approximate solution to concentration in a region with the trapezoidal boundary is derived with an instantaneous line source. The concentration in the trapezoidal open-channel flow is calculated analytically consequently. The analytical equation indicates that the slope angle has great influence on the concentration distribution and the concentrations will drop off with the slope angle following a hyperbolic law. The approximate solution is verified with the numerical solution to the diffusion equation of concentration, which represents physical mixing processes of the pollutant. The comparison illuminates that the solutions agree with each other very well except the concentrations in the region nearby the source and it can be a reliable tool for the evaluation of the scope of the mixing zone in natural rivers.