确定河流纵向弥散系数的正态分布图解法

The Normal Distribution Graphics Method for Determining the Longitudinal Dispersive Coefficient of River

许多学者对弥散现象进行了大量研究,提出许多确定弥散系数的方法,但受限于水流结构的复杂性,至今研究还停留在试验性阶段。本文以一维稳态河流水质污染模型的解析解为基础,通过拉普拉斯变换,将模型解析解转化为期望值a=ut、均方差δ=2Et的正态分布方程。提出分别采用单测站(时间浓度分布)与多测站(空间浓度分布)方法测定河水污染物浓度,根据标准正态概率密度函数的对称性,确定求解河流纵向弥散系数的正态分布图解法以及相应公式。对于同一问题,时间浓度分布得到的c/c0—t分布图较空间浓度分布得到的c/c0—x分布图更接近于正态分布,则采用单测站计算方法更适于河流水团示踪试验数据分析。最后通过实例分析进行验证。

Studies of dispersive phenomena have been carried into execution by many scholars and it has advanced a great deal of methods to solve the problems of dispersive coefficient. However, limiting to the complexity of current configuration, the studies are still at the test phases. Based on the analytic solution of 1-D steady water quality model for river flow,it has been transformed as normal distribution equation with a=ut and δ=2Et by Laplace transformation.Separately introducing single station(temporal concentration distribution) and multiple stations(spatial concentration distribution) methods to measure concentration of pollution,and deducing normal distribution graphics method and the relevant formula on the based of symmetry of normal probability density function. For the same situation, graphic of c/c_0—t is more approach normal distribution compared with graphic of c/c_0—x ,then single station method is more suitable for analysis of experimental data.It had also been validated by application of an example.